Image coding method, image decoding method, image coding apparatus, and image decoding apparatus

ABSTRACT

An image coding method, comprising: subtracting a prediction signal from the input image signal for each coding unit, thereby generating respective prediction error signals; performing orthogonal transform and quantization on a corresponding one of the prediction error signals for each transform unit, eventually generating quantization coefficients; and coding pieces of management information indicating a structure of the transform units and the quantization coefficients into a tree structure. Each of the transform units corresponds to a corresponding one of leaf nodes in the tree structure. In the coding, for each leaf node, management information and a quantization coefficient are coded, eventually generating a coded signal in which the coded management information and the coded quantization coefficient are arranged in succession for each leaf node.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of Application No. 13/710,932,filed Dec. 11, 2012, which claims the benefit of U.S. Provisional PatentApplication No. 61/570,865 filed Dec. 15, 2011. The entire disclosuresof the above-identified applications, including the specification,drawings and claims are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

One or more exemplary embodiments disclosed herein relate generally toimage coding methods, image decoding methods, image coding apparatuses,image decoding apparatuses, and image coding/decoding apparatuses.

BACKGROUND ART

In order to compress audio data and video data, various audio codingstandards and video coding standards have been developed. Examples ofsuch video coding standards are International Telecommunication UnionTelecommunication Standardization Sector (ITU-T) standard called H.26×and International Organization for Standardization/InternationalElectrotechnical Commission (ISO/IEC) standard called MPEG-x (seeNon-Patent Literature 1, for example). The latest video coding standardis called H.264/MPEG-4AVC. Recently, a new-generation coding standardcalled High Efficiency Video Coding (HEVC) has been examined.

CITATION LIST Non Patent Literature

-   [NPL 1] ISO/IEC 14496-10 “MPEG-4 Part10 Advanced Video Coding”

SUMMARY OF INVENTION Technical Problem

In such image coding methods and image decoding method, it has beendemanded to reduce a data amount in a memory for temporarily holdingdata used in coding or decoding.

In order to address the above, one non-limiting and exemplary embodimentprovides an image coding method and an image decoding method which arecapable of reducing a data amount in a memory for temporarily holdingdata used in coding or decoding.

Solution to Problem

In one general aspect, the techniques disclosed here feature, there isprovided an image coding method, comprising: splitting an input imagesignal into a plurality of coding units, and subtracting a predictionsignal from the input image signal for each of the coding units,eventually generating prediction error signals of the respective codingunits; splitting each of the coding units into a plurality of transformunits, and performing orthogonal transform and quantization on acorresponding one of the prediction error signals for each of thetransform units, eventually generating quantization coefficients of therespective coding units; and coding pieces of management information andthe quantization coefficients into a tree structure, the pieces ofmanagement information indicating a structure of the transform units,wherein each of the transform units corresponds to a corresponding oneof leaf nodes in the tree structure, and in the coding, for each of theleaf nodes, a corresponding piece of the management information and acorresponding one of the quantization coefficients are coded, eventuallygenerating a coded signal in which the coded corresponding piece of themanagement information and the coded corresponding one of thequantization coefficients are arranged in succession for the each of theleaf nodes.

These general and specific aspects may be implemented using a system, amethod, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or any combinationof systems, methods, integrated circuits, computer programs, orcomputer-readable recording media.

Additional benefits and advantages of the disclosed embodiments will beapparent from the Specification and Drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the Specification and Drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

Advantageous Effects of Invention

One non-limiting and exemplary embodiment provides an image codingmethod and an image decoding method which are capable of reducing a dataamount in a memory for temporarily holding data used in coding ordecoding.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the disclosure willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present disclosure.

FIG. 1 is a flowchart of coding according to a comparison example.

FIG. 2 is a block diagram of an image coding apparatus according toEmbodiment 1.

FIG. 3 is a block diagram of an image decoding apparatus according toEmbodiment 1.

FIG. 4A is a diagram showing an example of a TU according to Embodiment1.

FIG. 4B is a diagram showing an example of a TU according to Embodiment1.

FIG. 5 is a diagram showing an example of a tree structure according toEmbodiment 1.

FIG. 6 is a flowchart of coding according to Embodiment 1.

FIG. 7 is a flowchart of coding a split information tree according toEmbodiment 1.

FIG. 8 is a flowchart of coding a transform coefficient tree accordingto Embodiment 1.

FIG. 9 is a block diagram of an entropy decoding unit according toEmbodiment 1.

FIG. 10A is a diagram showing an example of coded signals according toEmbodiment 1.

FIG. 10B is a diagram showing an example of coded signals according toEmbodiment 2.

FIG. 11 is a flowchart of coding according to Embodiment 2.

FIG. 12A is a flowchart of a part of coding according to Embodiment 2.

FIG. 12B is a flowchart of a part of coding according to Embodiment 2.

FIG. 13 is a block diagram of an entropy decoding unit according toEmbodiment 2.

FIG. 14A is a diagram for explaining CBF coding according to Embodiment2.

FIG. 14B is a diagram for explaining CBF coding according to Embodiment2.

FIG. 14C is a diagram for explaining CBF coding according to Embodiment2.

FIG. 14D is a diagram for explaining CBF coding according to Embodiment2.

FIG. 15 is a flowchart of coding according to Embodiment

FIG. 16 is a flowchart of coding according to Embodiment 4.

FIG. 17 is a flowchart of another coding according to Embodiment 4.

FIG. 18A is a diagram showing an example of an order of coding CBFs andtransform coefficients according to Embodiment 5.

FIG. 18B is a diagram showing an example of an order of coding CBFs andtransform coefficients according to Embodiment 5.

FIG. 18C is a diagram showing an example of an order of coding CBFs andtransform coefficients according to Embodiment 5.

FIG. 19A is a diagram showing an example of an order of coding CBFs andtransform coefficients according to Embodiment 5.

FIG. 19B is a diagram showing an example of an order of coding CBFs andtransform coefficients according to Embodiment 5.

FIG. 20 is a flowchart of coding according to Embodiment 5.

FIG. 21A is a diagram showing an example of an order of coding CBFs andtransform coefficients according to Embodiment 5.

FIG. 21B is a diagram showing an example of an order of coding CBFs andtransform coefficients according to Embodiment 5.

FIG. 22A is a flowchart of coding according to Embodiment 6.

FIG. 22B is a flowchart of coding according to Embodiment 6.

FIG. 23 is a diagram showing an example of a syntax according toEmbodiment 6.

FIG. 24A is a diagram showing an example of a syntax according toEmbodiment 6.

FIG. 24B is a diagram showing an example of a syntax according toEmbodiment 6.

FIG. 24C is a diagram showing an example of a syntax according toEmbodiment 6.

FIG. 25A is a flowchart of coding according to Embodiment 7.

FIG. 25B is a flowchart of unified transform according to Embodiment 7.

FIG. 26 shows an overall configuration of a content providing system forimplementing content distribution services;

FIG. 27 shows an overall configuration of a digital broadcasting system;

FIG. 28 shows a block diagram illustrating an example of a configurationof a television;

FIG. 29 shows a block diagram illustrating an example of a configurationof an information reproducing/recording unit that reads and writesinformation from and on a recording medium that is an optical disk;

FIG. 30 shows an example of a configuration of a recording medium thatis an optical disk;

FIG. 31A shows an example of a cellular phone;

FIG. 31B is a block diagram showing an example of a configuration of acellular phone;

FIG. 32 illustrates a structure of multiplexed data;

FIG. 33 schematically shows how each stream is multiplexed inmultiplexed data;

FIG. 34 shows how a video stream is stored in a stream of PES packets inmore detail;

FIG. 35 shows a structure of TS packets and source packets in themultiplexed data;

FIG. 36 shows a data structure of a PMT;

FIG. 37 shows an internal structure of multiplexed data information;

FIG. 38 shows an internal structure of stream attribute information;

FIG. 39 shows steps for identifying video data;

FIG. 40 shows an example of a configuration of an integrated circuit forimplementing the moving picture coding method and the moving picturedecoding method according to each of Embodiments;

FIG. 41 shows a configuration for switching between driving frequencies;

FIG. 42 shows steps for identifying video data and switching betweendriving frequencies;

FIG. 43 shows an example of a look-up table in which video datastandards are associated with driving frequencies;

FIG. 44A is a diagram showing an example of a configuration for sharinga module of a signal processing unit; and

FIG. 44B is a diagram showing another example of a configuration forsharing a module of the signal processing unit.

DESCRIPTION OF EMBODIMENTS

(Underlying Knowledge Forming Basis of the Present Disclosure)

In relation to the disclosures in the Background section, the inventorshave found the following problem.

The following describes a coding method and a decoding method accordingto the disclosed comparison example.

FIG. 1 is a flowchart of the coding method according to the comparisonexample.

A picture (in other words, a frame) is split into macroblocks eachhaving the same size of 16 pixels×16 pixels. The plurality ofmacroblocks are coded, for example, sequentially in a raster scan order.FIG. 1 shows coding of one macroblock.

First, one of various orthogonal transform sizes is selected as atransform size for a current macroblock to be coded. The transform sizeis smaller than a size of the macroblock. For example, the transformsize is 4 pixels×4 pixels or 8 pixels×8 pixels. Hereinafter, the unitfor transform is referred to as a “transform unit (TU)”. Then,information indicating the selected transform size is coded (S101). Aflag indicating the transform size is, for example, transform_size_flag.

Next, a CBF is coded (S102). Here, a CBF refers to flag informationindicating whether or not a transform coefficient (quantizationcoefficient) of a TU exists.

Next, a TU is selected. For example, a plurality of TUs are sequentiallyselected in a Z scan order, and the selected TU is applied with thefollowing processing.

If the CBF is true (Yes at S104), then a transform coefficient of thecurrent TU is coded (S105). On the other hand, if the CBF is false (Noat S104), then the transform coefficient of the current TU is not coded.The series of steps S103 to S105 are performed on each of the TUsincluded in the current macroblock (S106).

Decoding is also performed in the same order as shown in FIG. 1. Inother words, decoding can be explained by replacing the “coding” by“decoding” in the above description.

Here, in order to efficiently code a picture, flexible selection oftransform size is important. However, the inventors have found that adata amount of information indicating a transform size is increased, asthe flexibility in selecting a transform size is improved.

According to an exemplary embodiment disclosed herein to solve theabove-described problems, an image coding method, comprising: splittingan input image signal into a plurality of coding units, and subtractinga prediction signal from the input image signal for each of the codingunits, eventually generating prediction error signals of the respectivecoding units; splitting each of the coding units into a plurality oftransform units, and performing orthogonal transform and quantization ona corresponding one of the prediction error signals for each of thetransform units, eventually generating quantization coefficients of therespective coding units; and coding pieces of management information andthe quantization coefficients into a tree structure, the pieces ofmanagement information indicating a structure of the transform units,wherein each of the transform units corresponds to a corresponding oneof leaf nodes in the tree structure, and in the coding, for each of theleaf nodes, a corresponding piece of the management information and acorresponding one of the quantization coefficients are coded, eventuallygenerating a coded signal in which the coded corresponding piece of themanagement information and the coded corresponding one of thequantization coefficients are arranged in succession for the each of theleaf nodes.

By the method, a piece of management information and a quantizationcoefficient of each of transform units are continuously coded.Therefore, each of the image coding apparatus and the image decodingapparatus does not need to cause a memory to hold pieces of managementinformation of other transform units. As described above, the imagecoding method can reduce a data amount of a memory for temporarilystoring pieces of data to be used in coding or decoding.

It is possible that the pieces of the management information includesrespective pieces of split information each of which corresponds to acorresponding one of nodes in the tree structure and indicates whetheror not a transform unit corresponding to the corresponding one of thenodes is to be further split.

It is also possible that the pieces of the management informationincludes respective first flags each of which corresponds to at leastone of the nodes in the tree structure and indicates whether or not aquantization coefficient corresponding to each of the at least one ofthe nodes exists.

It is further possible that in the coding, it is determined whether ornot a value of the first flag of a current node at a current level canbe uniquely identified by at least one of (a) the first flag at a levelupper than the current level and (b) the first flag of a different nodeat the current level, and when it is determined that the value of thefirst flag of the current node can be uniquely identified, the firstflag of the current node is not coded.

Therefore, the image coding method can reduce a coding amount of thecoded signal.

It is further possible that the coding includes coding a differencequantization step at the each of the leaf nodes in the coded signal, thecoded difference quantization step being arranged at a positioncorresponding to the each of the leaf nodes in the tree structure, andthe difference quantization step indicates, in the performing oforthogonal transform and quantization, a difference between aquantization step that has most recently been used and a quantizationstep that is to be used for a current transform unit.

By the method, the image coding method can arrange the differencequantization step and the transform coefficient at close positions inthe coded signal. As a result, the image coding method can reduce anamount of a memory for temporarily storing data in the image decodingapparatus.

It is further possible that the coding includes coding a differencequantization step at a root of the tree structure in the coded signal,the coded difference quantization step being arranged at a positioncorresponding to the root, and the difference quantization stepindicates, in the performing of orthogonal transform and quantization, adifference between a quantization step that has most recently been usedand a quantization step that is to be used for a current transform unit.

By the above method, the image coding method can reduce a coding amountof the coded signal.

It is further possible that each of the quantization coefficientsincludes a luminance quantization coefficient and a chrominancequantization coefficient, and the first flag includes a second flag anda third flag, the second flag indicating whether or not the luminancequantization coefficient exists, and the third flag indicating whetheror not the chrominance quantization coefficient exists, wherein in thecoding, for each of the at least one of the nodes, the second flag iscoded after coding the third flag, thereby generating the coded signalin which the coded second flag is arranged after the coded third flag.

It is further possible that each of the quantization coefficientsincludes a luminance quantization coefficient, a chrominance Cbquantization coefficient, and a chrominance Cr quantization coefficient,the first flag includes a second flag, a third flag, and a fourth flag,the second flag indicating whether or not the luminance quantizationcoefficient exists, the third flag indicating whether or not thechrominance Cb quantization coefficient exists, and the fourth flagindicating whether or not the chrominance Cr quantization coefficientexists, and in the coding, for each of the at least one of the nodes,the third flag, the fourth flag, the second flag, the luminancequantization coefficient, the chrominance Cb quantization coefficient,and the chrominance Cr quantization coefficient are coded in order,thereby generating the coded signal in which the coded third flag, thecoded fourth flag, the coded second flag, the coded luminancequantization coefficient, the coded chrominance Cb quantizationcoefficient, and the coded chrominance Cr quantization coefficient arearranged in order.

According to another exemplary embodiment disclosed herein, it isfurther possible that an image decoding method, comprising: decoding acoded signal to generate quantization coefficients and pieces ofmanagement information, the quantization coefficients each correspondingto a corresponding one of transform units, and the pieces of themanagement information indicating a structure of the transform units;performing inverse quantization and inverse transform on each of thequantization coefficients, eventually generating prediction errorsignals of the respective transform units; and adding at least one ofthe prediction error signals to a prediction signal for each of codingunits each including the transform units, eventually generating decodedsignals for each of the coding units, the quantization coefficients andthe pieces of the management information have a tree structure, each ofthe transform units corresponds to a corresponding one of leaf nodes inthe tree structure, and the decoding includes decoding, for each of theleaf nodes, a coded piece of the management information and a codedquantization coefficient which are arranged in succession in the codedsignal for the each of the leaf nodes.

By the method, a piece of management information and a quantizationcoefficient of each of transform units are continuously coded.Therefore, the image decoding apparatus does not need to cause a memoryto hold pieces of management information of other transform units. Asdescribed above, the image decoding method can reduce a data amount of amemory for temporarily storing pieces of data to be used in decoding.

It is possible that the pieces of the management information includesrespective pieces of split information each of which corresponds to acorresponding one of nodes in the tree structure and indicates whetheror not a transform unit corresponding to the corresponding one of thenodes is to be further split.

It is also possible that the pieces of the management informationincludes respective first flags each of which corresponds to at leastone of the nodes in the tree structure and indicates whether or not aquantization coefficient corresponding to each of the at least one ofthe nodes exists.

It is further possible that in the decoding, it is determined whether ornot a value of the first flag of a current node at a current level canbe identified by at least one of (a) the first flag at a level upperthan the current level and (b) the first flag of a different node at thecurrent level, and when it is determined that the value of the firstflag of the current node can be uniquely identified, the first flag ofthe current node is not generated by decoding.

By this method, a coding amount of the coded signal can be reduced.

It is further possible that the decoding includes decoding a differencequantization step at a current leaf node in the coded signal, thedifference quantization step being arranged at a position correspondingto the current leaf node in the tree structure, and the differencequantization step indicates, in the performing of inverse quantizationand inverse orthogonal transform, a difference between a quantizationstep that has most recently been used and a quantization step that is tobe used for a current transform unit.

By the method, a difference quantization step and a transformcoefficient are arranged close to each other in a coded signal. As aresult, the image decoding method can reduce an amount of a memory fortemporarily storing data in the image decoding apparatus.

It is further possible that the decoding includes decoding a differencequantization step at a root of the tree structure in the coded signal,the difference quantization step being coded arranged at a positioncorresponding to the root, and the difference quantization stepindicates, in the performing of inverse quantization and inverseorthogonal transform, a difference between a quantization step that hasmost recently been used and a quantization step that is to be used for acurrent transform unit.

By this method, a coding amount of the coded signal can be reduced.

It is further possible that each of the quantization coefficientsincludes a luminance quantization coefficient and a chrominancequantization coefficient, and the first flag includes a second flag anda third flag, the second flag indicating whether or not the luminancequantization coefficient exists, and the third flag indicating whetheror not the chrominance quantization coefficient exists, in the codedsignal, the second flag that is coded is arranged after the third flagthat is coded, in the decoding, the second flag that is coded is decodedafter decoding the third flag that is coded, for each of the at leastone of the nodes.

It is further possible that each of the quantization coefficientsincludes a luminance quantization coefficient, a chrominance Cbquantization coefficient, and a chrominance Cr quantization coefficient,the first flag includes a second flag, a third flag, and a fourth flag,the second flag indicating whether or not the luminance quantizationcoefficient exists, the third flag indicating whether or not thechrominance Cb quantization coefficient exists, and the fourth flagindicating whether or not the chrominance Cr quantization coefficientexists, and the third flag that is coded, the fourth flag that is coded,the second flag that is coded, the luminance quantization coefficientthat is coded, the chrominance Cb quantization coefficient that iscoded, and the chrominance Cr quantization coefficient that is coded arearranged in order in the coded signal, and in the decoding, for each ofthe at least one of the nodes, the third flag that is coded, the fourthflag that is coded, the second flag that is coded, the luminancequantization coefficient that is coded, the chrominance Cb quantizationcoefficient that is coded, and the chrominance Cr quantizationcoefficient that is coded are decoded in order.

According to still another exemplary embodiment disclosed herein, animage coding apparatus which performs the above-described image codingmethod.

By the method, a piece of management information and a quantizationcoefficient of each of transform units are continuously coded.Therefore, each of the image coding apparatus and the image decodingapparatus does not need to cause a memory to hold pieces of managementinformation of other transform units. As described above, the imagecoding apparatus can reduce a data amount of a memory for temporarilystoring pieces of data to be used in coding or decoding.

According to still another exemplary embodiment disclosed herein, animage decoding apparatus which performs the above-described imagedecoding method.

By the method, a piece of management information and a quantizationcoefficient of each of transform units are continuously coded.Therefore, the image decoding apparatus does not need to cause a memoryto hold pieces of management information of other transform units. Asdescribed above, the image decoding apparatus can reduce a data amountof a memory for temporarily storing pieces of data to be used indecoding.

According to still another exemplary embodiment disclosed herein, animage coding/decoding apparatus includes the above-described imagecoding apparatus and the above-described image decoding apparatus.

These general and specific aspects may be implemented using a system, amethod, an integrated circuit, a computer program, or acomputer-readable recording medium such as a CD-ROM, or any combinationof systems, methods, integrated circuits, computer programs, orcomputer-readable recording media.

The following describes embodiments with reference to the drawings.

Each of the exemplary embodiments described below shows a general orspecific example. The numerical values, shapes, materials, structuralelements, the arrangement and connection of the structural elements,steps, the processing order of the steps etc. shown in the followingexemplary embodiments are mere examples, and therefore do not limit thescope of the appended Claims and their equivalents. Therefore, among thestructural elements in the following exemplary embodiments, structuralelements not recited in any one of the independent claims are describedas arbitrary structural elements.

(Embodiment 1)

The image coding apparatus according to Embodiment 1 splits a block as aunit to be coded, hierarchically into a plurality of the transformunits. In addition, the image coding apparatus codes, into a treestructure, (a) pieces of management information indicating a structureof the transform units, and (b) transform coefficients. As a result, theimage coding apparatus is capable of suppressing the increase of piecesof information indicating the structure of the transform units, and alsocapable of increasing the flexibility in selecting a transform size.

First, structures of an image coding apparatus and an image decodingapparatus are described.

FIG. 2 is a block diagram of the image coding apparatus 100 according tothe present embodiment. The image coding apparatus 100 codes, forexample, audio data and video data at a low bit-rate.

The image coding apparatus 100 shown in FIG. 2 codes an input imagesignal 101 to generate a coded signal 191. The image coding apparatus100 includes a subtractor 110, a transforming unit 120, a quantizationunit 130, an inverse quantization unit 140, an inverse transforming unit150, an adder 160, a memory 170, a prediction unit 180, and an entropycoding unit 190.

Here, a picture (in other words, frame) is split into a plurality ofCoding Units (CU) to be coded. Each picture is therefore coded on aCU-by-CU basis. Each of the CUs is further split into one or moreTransform Units (TU).

The subtractor 110 splits an input image signal 101 into a plurality ofCUs. Then, for each of the CUs, the subtractor 110 subtracts aprediction signal 181 from the input image signal 101 to generate aprediction error signal 111 (transform input signal), and provides thegenerated prediction error signal 111 to the transforming unit 120.

The transforming unit 120 splits a CU into one or more TUs. Then, foreach of the TUs, the transforming unit 120 performs frequency transformon a corresponding prediction error signal 111 to generate a transformoutput signal 121. More specifically, the transforming unit 120transforms, from a temporal-spatial domain to a frequency domain, theprediction error signal 111 or the transform input signal generated byperforming certain processing on the prediction error signal 111. As aresult, the transforming unit 120 generates the transform output signal121 having decreased correlation.

The quantization unit 130 quantizes the transform output signal 121 foreach of the TUs, thereby generating a quantization coefficient 131having a small total amount of data.

The entropy coding unit 190 codes the quantization coefficient 131 byusing an entropy coding algorithm, thereby generating a coded signal 191having further compressed redundancy.

For each of the TUs, the inverse quantization unit 140 inverselyquantizes the quantization coefficient 131 to generate a decodedtransform output signal 141. For each of the TUs, the inversetransforming unit 150 inversely transforms the decoded transform outputsignal 141 to generate a decoded transform input signal 151.

For each of the CUs, the adder 160 adds the decoded transform inputsignal 151 with a prediction signal 181 to generate a decoded signal161. The memory 170 stores the decoded signal 161.

For each of the CUs, the prediction unit 180 obtains a predeterminedsignal from the memory 170 according to a prediction method such asintra prediction or inter prediction, and generates a prediction signal181 according to a predetermined method based on the prediction method.More specifically, the prediction unit 180 determines the predictionmethod to achieve a maximum coding efficiency, and generates theprediction signal 181 according to the determined prediction method.Furthermore, the entropy coding unit 190 performs entropy coding on theinformation indicating the prediction method, as needed.

Here, the inverse quantization unit 140, the inverse transforming unit150, the adder 160, the memory 170, and the prediction unit 180 areincluded also in the image decoding apparatus. The decoded signal 161corresponds to a reproduced image signal (decoded signal 261) generatedby the image decoding apparatus.

FIG. 3 is a block diagram of the image decoding apparatus. The imagedecoding apparatus 200 shown in FIG. 3 decodes a coded signal 191 togenerate a decoded signal 261. The image decoding apparatus 200 includesan inverse quantization unit 240, an inverse transforming unit 250, anadder 260, a memory 270, a prediction unit 280, and an entropy decodingunit 290.

The entropy decoding unit 290 performs entropy decoding on the codedsignal 191 to generate a quantization coefficient 231 and a predictionmethod 291.

For each of TUs, the inverse quantization unit 240 inversely quantizesthe quantization coefficient 231 to generate a decoded transform outputsignal 241. The inverse transforming unit 250 inversely transforms thedecoded transform output signal 241 to generate a decoded transforminput signal 251.

For each of CUs, the adder 260 adds the decoded transform input signal251 with a prediction signal 281 to generate a decoded signal 261. Thedecoded signal 261 is a reproduced image generated by the image decodingapparatus 200. The decoded signal 261 is outputted as an output signalof the image decoding apparatus 200, and also stored into the memory270.

For each of the CUs, the prediction unit 280 obtains a predeterminedsignal from the memory 270 according to the prediction method 291, andgenerates a prediction signal 281 according to a predetermined methodbased on the prediction method 291.

Hereinafter, the quantization coefficients 131 and 231 are referred toalso as “transform coefficients” or “block transform coefficients”.

According to the present embodiment, in order to flexibly select atransform size from among various transform sizes ranging from large tosmall, splitting to Transform Units (TUs) is expressed in a treestructure. In the tree structure, in order to define nodes up to nodesat the ends (leaf nodes), transform unit split information (TUS:split_transform_flag) that is flag information indicating whether or notTU splitting is to be performed is coded.

Each of FIGS. 4A and 4B shows an example of TUs. For example, as shownin FIG. 4, a single CU (TU0) can be split into four TUs that are TU1 toTU4. Each of the TU1 to TU4 can be further split into four TUs. Forexample, in the example shown in FIG. 4B, the TU1 shown in FIG. 4A isfurther split into four TUs that are TU5 to TU8. As described above, theTU splitting is hierarchically performed.

FIG. 5 is a diagram showing a tree structure of the TUs shown in FIG.4B. As shown in FIG. 5, a root of the tree structure is the CU (TU0).The leaf nodes in the tree structure are the respective split TUs.

Each of the nodes in the tree structure has split information (TUS). Inother words, a TUS corresponds to a corresponding one of the nodes inthe tree structure, and indicates whether or not a TU corresponding tothe node is to be further split. A value “1” of a TUS means that a TUcorresponding to the node is to be further split. On the other hand, avalue “0” of a TUS means that the TU corresponding to the node is not tobe split.

The leaf node indicating a TUS as “0” further has a CBF indicatingwhether or not there is a transform coefficient (coeff) corresponding tothe leaf node. A value “1” of a CBF means that the node has thetransform coefficient. On the other hand, a value “0” of a CBF meansthat the node does not have a transform coefficient. It should be notedthat a CBF may be included in nodes except the leaf nodes, which will bedescribed later in more detail. In other words, a CBF corresponds to atleast one of nodes in the tree structure, and is the first flagindicating whether there is a quantization coefficient 131 correspondingto the node.

FIG. 6 is a flowchart of an image coding method according to the presentembodiment. FIG. 6 shows coding of a single CU.

First, the image coding apparatus 100 (entropy coding unit 190) codes atree structure (split information tree: transform_split_tree) of TUSs asinformation indicating which transform size is to be performed on the CU(S111). More specifically, the image coding apparatus 100 codes, in to atree structure, pieces of management information (TUS and CBF)indicating a structure of a plurality of transform units.

Next, the image coding apparatus 100 codes the tree structure (transformcoefficient tree: transform_coeff_tree) of transform coefficientsincluding transform coefficients of respective TUs, according to thetransform sizes, the pieces of position information, and CBFs which areexpressed in the split information tree (S112). The above-describedseries of processes are performed on each of CUs.

The use of such tree structure expression can set a size of a transformsize spatially or partially in a CU, so as to achieve a maximum codingefficiency depending on features and the like of image. Note that a CBFmay be coded at Step S112 not at Step S111.

The following describes coding (S111) of the split information tree.FIG. 7 is a flowchart of detailed steps in the coding (S111) of a splitinformation tree.

The coding of a split information tree is recursively defined. Therecursive level (hierarchy) of the tree structure is called a TransformDepth (TrD).

First, the image coding apparatus 100 codes a TUS of a certain TrD(S121). Next, the image coding apparatus 100 switches processing toanother according to the method of generating a prediction signal(S122). For example, if inter prediction (inter-picture prediction) isadopted, a data amount of a transform coefficient of chrominance signalis likely to be zero. Therefore, in the case where inter prediction isadopted (Yes at S122), then the image coding apparatus 100 codescbf_chroma that is the third flag indicating whether or not a transformcoefficient of a block of chrominance signal exists (S123).

Note that TUS may be exchanged with cbf_chroma in the coding order. Ifcbf_chroma is coded prior to a TUS, the image decoding apparatus 200obtains TUS information from a coded stream (coded signal 191), so as tominimize a wait time until it is determined (S124) based on the TUSwhether or not next splitting is to be performed. Thereby, if a TUS isstored in a high-speed cash memory or the like, it is possible to reducea memory amount and increase a processing speed.

Referring back to FIG. 7, the description continues. Next, the imagecoding apparatus 100 determines based on the TUS whether or not acurrent TU is to be further split into pieces (S124). If the TU is to besplit (Yes at S124), then the image coding apparatus 100 spatiallysplits the TU into four regions, and recursively codes the splitinformation tree for the split regions (S129). In other words, the imagecoding apparatus 100 performs the processing (5111) shown in FIG. 7 oneach of the split four TUs.

On the other hand, if the TU is not to be split (No at S124), then theimage coding apparatus 100 codes cbf_luma that is the second flagindicating whether or not a transform coefficient of luminance signal ofthe current TU exists (S125).

Next, the image coding apparatus 100 determines whether or not theprediction method used for the TU (CU) is inter prediction (S126). Ifthe inter prediction is used (Yes at S126), then the image codingapparatus 100 terminates the coding (S111) of the split information treefor the current node. On the other hand, if the inter prediction is notadopted (for example, intra prediction (intra-picture prediction) isadopted) (No at S126), then the image coding apparatus 100 codescbf_chroma (S127), and terminates the coding (S111) of the splitinformation tree for the node. If the above-described processing isrecursive processing for a lower level in the hierarchy, the processingshifts to another processing for an upper level of a recursive call (aparent node of the current node in the tree structure).

Then, if transform sizes and CBFs are expressed for all of the regionsin the CU, the coding (S111) of the split information tree is completed.

Next, the coding (S112) of a transform coefficient tree is described.FIG. 8 is a flowchart of the coding (S112) of a transform coefficienttree.

The coding of a split information tree is recursively defined. Theprocessing for coding a transform coefficient tree at a certainrecursive level depends on whether a previously coded TUS is true orfalse (S131). If a TUS is true (Yes at S131), then the image codingapparatus 100 splits the TU into four pieces, and recursively codes thetransform coefficient tree for the split regions (S136).

On the other hand, if the TU is not to be split (No at S131), then theprocessing is changed according to whether a previously coded cbf_lumais true or false (S132). If cbf_luma is true (Yes at S132), then theimage coding apparatus 100 codes a transform coefficient of luminancesignal of the TU (S133). On the other hand, if cbf_luma is false (No atS132), then the image coding apparatus 100 does not code the transformcoefficient of the luminance signal of the TU.

Next, the processing is changed depending on a previously codedcbf_chroma (S134). If cbf_chroma is true (Yes at S134), then the imagecoding apparatus 100 codes a transform coefficient of chrominance signalof the current CU (S135). On the other hand, if cbf_chroma is false (Noat S134), then the image coding apparatus 100 does not code thetransform coefficient of the chrominance signal of the current TU.

As described above, the processing for a certain leaf node is completed.If the above-described processing is recursive processing for a lowerlevel, the processing shifts to another processing for an upper level ofa recursive call (a parent node of the current node in the treestructure).

Then, when traverse (search or circuit) of the TUS tree structure iscompleted for all of the regions in the current CU and thereforetransform coefficients of TUs each having a CBF that is true have beencoded, the coding (S112) of a transform coefficient tree is completed.

Note that, in the flow described with reference to FIGS. 6, 7, and 8, if“coding” is replaced by “decoding”, a flow of decoding performed by theimage decoding apparatus 200 (entropy decoding unit 290) can beobtained.

Note also that the above-described procedure is not only the procedurefor coding or decoding, but also the order of arranging data of thecoded signal 191. More specifically, in the coded signal 191, pieces ofcoded data (TUS, CBF, and transform coefficient) are arranged in thesame order as the above-described procedure. The same goes for thesubsequent embodiments.

FIG. 9 is a block diagram of an entropy decoding unit 290A that is anexample of the entropy decoding unit 290 included in the image decodingapparatus 200. The entropy decoding unit 290A includes a branching unit311, a split information tree decoding unit 312, a TUS memory 313, a CBFmemory 314, a transform coefficient tree decoding unit 315, and atransform coefficient decoding unit 316.

The branching unit 311 (DeMux unit) selectively outputs a signalaccording to a type of the coded signal 191. More specifically, thebranching unit 311 provides the split information tree decoding unit 312with coded management information 321 included in the coded signal 191.The coded management information 321 includes a coded TUS and a codedCBF.

The split information tree decoding unit 312 decodes the codedmanagement information 321 to obtain the TUS and the CBF. The TUS isstored in the TUS memory 313 that is a temporary memory. In other words,all of TUSs in a current CU are temporarily stored in the TUS memory313. In addition, the CBF is stored into the CBF memory 314 that is atemporary memory. In other words, all CBFs in a current CU aretemporarily stored in the CBF memory 314.

After a TUS and a CBF have been decoded, the branching unit 311 providesthe transform coefficient tree decoding unit 315 with the codedtransform coefficient 322 included in the coded signal 191.

The transform coefficient tree decoding unit 315 reads a TUS from theTUS memory 313, and searches the tree structure for a node according tothe TUS. Then, the transform coefficient tree decoding unit 315 reads aCBF of the corresponding node from the CBF memory 314, and associatesthe coded transform coefficient with a transform unit having a CBF thatis true.

The transform coefficient decoding unit 316 performs entropy decoding onthe coded transform coefficient 322 for each TU, thereby generating atransform coefficient (quantization coefficient 231).

As described above, each of the image coding apparatus 100 and the imagedecoding apparatus 200 according to the present embodiment uses themanagement information having the tree structure, thereby reducing anoverhead of the management information. In other words, each of theimage coding apparatus 100 and the image decoding apparatus 200 cansuppress increase of information indicating a structure of transformunits, and also increase a flexibility in selecting a transform size.

Furthermore, each of the image coding apparatus 100 and the imagedecoding apparatus 200 uses two tree structures that are a splitinformation tree and a transform coefficient tree. As described above,it is possible to independently perform processing speed optimizationand the like for each of the tree structures.

(Embodiment 2)

In Embodiment 1, the two tree structures are used. In Embodiment 2,however, one tree structure is used to code management information andtransform coefficients.

The following describes a difference between the previously-describedEmbodiment 1 and Embodiment 2, with reference to FIGS. 10A and 10B. FIG.10A is a diagram showing an arrangement of coded management informationand coded transform coefficients which are included in a coded signal191 according to Embodiment 1 FIG. 10B is a diagram showing anarrangement of coded management information and coded transformcoefficients which are included in a coded signal 191 according toEmbodiment 2. The data shown in each of FIGS. 10A and 10B corresponds tothe tree structure shown in FIG. 5.

As shown in FIG. 10A, according to Embodiment 1, pieces of managementinformation included in a division information tree are arranged insuccession, and transform coefficients included in a transformcoefficient tree are arranged in another group. In other words,management information and a transform coefficient of the same TU arearranged in separated positions. Therefore, it is necessary totemporarily store, into the memory, management information which isdecoded prior to a transform coefficient.

According to Embodiment 2, on the other hand, a single tree structure isused to arrange both management information and a transform coefficientare arranged in succession for each of leaf nodes in the tree structure.Therefore, it is possible to reduce a data amount to be temporarilystored in the memory.

The following describes a coding method according to the presentembodiment. In the following description, the difference from Embodiment1 is mainly described and the overlapping explanation is not given.Furthermore, the same reference numerals are assigned to the identicalelements and steps in the drawings.

FIG. 11 is a flowchart of coding performed by the image coding apparatus100 according to the present embodiment. The image coding apparatus 100codes management information (TUS and CBF) and a transform coefficientby using a single transform unified tree.

First, the image coding apparatus 100 codes a TUS of a certain TrD(S121). Next, the processing is changed to another according to the TUS(S131). If the TUS is true (Yes at S131), then the image codingapparatus 100 spatially splits the TU into four regions, and recursivelycodes a transform unified tree for the split regions (S141).

On the other hand, if the TUS is false (No at S131), then the imagecoding apparatus 100 does not split the TU. In other words, the node isa leaf node. Here, the processing is changed to another according towhether cbf_luma coded in the transform unified tree is true or false(S132).

If cbf_luma is true (Yes at 5132), then the image coding apparatus 100codes a transform coefficient of luminance signal of the current TU(S133). On the other hand, if cbf_luma is false (No at S132), then theimage coding apparatus 100 does not code the transform coefficient ofthe luminance signal of the TU.

Next, the processing is changed according to whether cbf_chroma is trueor false (S134). If cbf_chroma is true (Yes at S134), then the imagecoding apparatus 100 codes a transform coefficient of chrominance signalof the current CU (S135). On the other hand, if cbf_chroma is false (Noat S134), then the image coding apparatus 100 does not code thetransform coefficient of the chrominance signal of the current TU.

As described above, the processing for a certain leaf node is completed.If the above-described processing is recursive processing for a lowerlevel in the hierarchy, the processing shifts to processing for an upperlevel of a recursive call (a parent node of the current node in the treestructure).

Then, if transform sizes, CBFs, and the like of all of the regions inthe current CU and the transform coefficients are coded, the coding ofthe transform unified tree is completed.

Embodiment 2 differs from Embodiment 1 in that the tree structureincludes pieces of management information and transform coefficients atthe leaf nodes. Embodiment 1 needs two processes for the treestructures, which are coding of the two tree structures (splitinformation tree and transform coefficient tree) and traverse of thetree structures. Embodiment 2, on the other hand, needs one process forthe tree structure in the coding method. Therefore, Embodiment 2 canreduce steps included in the image coding apparatus, the image decodingapparatus, the image coding method, and the image decoding method.

As described above, according to the present embodiment, the imagecoding apparatus 100 codes, into a single tree structure, pieces ofmanagement information and quantization coefficients 131 which indicatea structure of a plurality of TUs. Here, each of the TUs corresponds toa corresponding one of the leaf nodes in the tree structure. Inaddition, the image coding apparatus 100 codes, for each of the leafnodes, management information and a quantization coefficient 131 whichcorrespond to the leaf node, and generates a coded signal 191 in whichthe coded management information and the coded quantization coefficientare arranged in succession.

Moreover, the image decoding apparatus 200 decodes the coded signal 191to obtain respective quantization coefficients 231 of the TUs and piecesof management information (TUS and CBF) indicating the structure of theTUs. Here, the pieces of management information and the quantizationcoefficients 231 form a single tree structure. Here, each of the TUscorresponds to a corresponding one of the leaf nodes in the treestructure. Then, for the coded signal 191, the image decoding apparatus200 decodes, for each of the leaf nodes, a coded management informationand a coded quantization coefficients which are arranged in successionfor the leaf node.

Each of FIGS. 12A and 12B is a flowchart of processing performed on aCBF and a transform coefficient of chrominance signal. The processingshown in each of FIGS. 12A and 12B is included in the flowchart of FIG.11.

The image coding apparatus 100 codes cbf_chroma at a certain stage inthe transform unified tree (S123). If cbf_chroma is true (Yes at S134),then the image coding apparatus 100 codes a transform coefficient ofchrominance signal of the current CU (S135).

For the sake of simplicity in the description, Cb and Cr of chrominanceare not distinguished from each other in FIG. 12A. In practice, Cb isdistinguished from Cr as shown in FIG. 12B.

As shown in FIG. 12B, at a certain stage in the transform unified tree,the image coding apparatus 100 codes cbf_cb that is the third flagindicating whether there is a transform coefficient of chrominance Cb(S123A). In addition, at a certain stage in the transform unified tree,the image coding apparatus 100 codes cbf_cr that is the fourth flagindicating whether or not there is a transform coefficient ofchrominance Cr (S123B). After that, if cbf_cb is true (Yes at S134A),then the image coding apparatus 100 codes the transform coefficient ofthe chrominance Cb of the current CU (S135A). On the other hand, ifcbf_cr is true (Yes at S134B), then the image coding apparatus 100 codesthe transform coefficient of the chrominance Cr of the current TU(S135B).

FIG. 13 is a block diagram of an entropy decoding unit 290B that is anexample of the entropy decoding unit 290 included in the image decodingapparatus 200 according to Embodiment 2. The entropy decoding unit 290Bincludes a transform unified tree decoding unit 317 and a transformcoefficient decoding unit 316.

From among the coded signal 191, the coded TUS, CBF, and transformcoefficient, namely, the coded signals included in the transform unifiedtree, are provided to the transform unified tree decoding unit 317. Thetransform unified tree decoding unit 317 decodes a TU transform unitsize and a position according to the TUS tree structure. In addition,the transform unified tree decoding unit 317 decodes a CBF as needed,and outputs a coded transform coefficient of a TU if the CBF is true.

The transform coefficient decoding unit 316 performs entropy decoding onthe coded transform coefficient provided from the transform unified treedecoding unit 317, thereby generating a transform coefficient(quantization coefficient 231).

The entropy decoding unit 290B shown in FIG. 13 differs from the entropydecoding unit 290A shown in FIG. 9 in that the TUS memory 313 and theCBF memory 314 are not required. As described above, the image decodingapparatus 200 according to the present embodiment can reduce a memorysize.

Note that the image coding apparatus 100 can eliminate coding of flagssuch as cbf_chroma, cbf_luma, cbf_cb, and cbf_cr under certainconditions. It is thereby possible to reduce a data amount of the codedsignal 191. The following describes the processing with reference toFIGS. 14A to 14D.

FIG. 14A is a diagram for explaining a normal case where a CBF flag iscoded for each of four split regions. FIG. 14B is a diagram of oneexample where coding is eliminated. Here, it is known that any of thesefour blocks has a transform coefficient. In this case, if CBFs of blocksat the upper left, at the upper right, and at the lower left are all“0”, then a CBF of a block at the lower right should be “1”. This isapparent without reference to a CBF flag of the block at the lowerright. Therefore, coding of the CBF flag of the block at the lower rightcan be eliminated.

FIG. 14C is a diagram of another example, showing four blocks at acertain TrD=d and a block TrD=d−1 at a level that is upper than thelevel of the four blocks. If a CBF is “1” for the upper-level blockTrD=d−1, at least one of the blocks TrD=d that are generated bysplitting the upper-hierarchy block and are at a lower level has atransform coefficient. In other words, in this case, one of the blocksat the lower level TrD=d has a CBF=1. In this case, like the above case,if CBFs of blocks at the upper left, at the upper right, and at thelower left are all “0”, then a CBF of a block at the lower right shouldbe “1”. Therefore, coding of the CBF of the block at the lower right canbe eliminated.

Likewise, FIG. 14D is a diagram showing an example where cbf_chroma isfirst coded to cause cbf_luma to depend on the coded cbf_chroma. Forcbf_luma of the four blocks at TrD=d, if pieces of cbf_luma of allblocks at the upper left, at the upper right, and at the lower left are“0” and pieces of cbf_chroma (cbf_cb and cbf_cr) of two blocks at anupper level are “0”, it is sure that cbf_luma of the last block is “1”.Therefore, coding of cbf_luma of the block can be eliminated.

As described above, there is a case where a CBF flag can be eliminated.In the present embodiment, it is possible to combine eliminations undersuch conditions in coding or decoding a CBF flag.

As described above, the image coding apparatus 100 determines whether ornot a value of a CBF flag of a current node at a current level can beuniquely identified by at least one of (a) a CBF flag at an upper leveland (b) CBF flags of different nodes at the current level. If the valueof the CBF flag of the current node can be uniquely identified, the CBFflag of the current node is not coded. Furthermore, the image decodingapparatus 200 determines whether or not a value of a CBF of a currentnode at a current level can be uniquely identified by at least one of(a) a CBF flag at an upper level and (b) CBF flags of different nodes atthe current level. If the value of the CBF of the current node can beuniquely identified, the CBF flag of the current node is not decoded.

Thus, the image coding apparatus 100 according to the present embodimentcodes (a) management information indicating a size of a transform unit,a position, and the like and (b) a transform coefficient into a singletree structure. The image coding apparatus 100 and the image decodingapparatus 200 can thereby reduce a data amount in a used memory andreduce steps in processing.

Note that, in the flow described with reference to FIGS. 11, 12A, and12B, if “coding” is replaced by “decoding”, a flow of decoding performedby the image decoding apparatus 200 (entropy decoding unit 290B) can beobtained.

(Embodiment 3)

Embodiment 3 is a variation of the above-described Embodiment 2.

FIG. 15 is a flowchart of coding according to the present embodiment.The same reference numerals in FIG. 11 are assigned to the identicalsteps in FIG. 15, and therefore differences between FIG. 11 and FIG. 15are mainly described.

After Step S121, the image coding apparatus 100 determines processingaccording to a method of generating a prediction signal (S122). Morespecifically, if inter prediction is adopted (Yes at S122), then theimage coding apparatus 100 codes cbf_chroma (S123).

Next, the image coding apparatus 100 determines based on a TUS whetheror not a current TU is to be further split into pieces (S124). If the TUis to be split (Yes at S124), then the image coding apparatus 100spatially split the TU into four regions, and recursively codes atransform unified tree for the split regions (S141).

On the other hand, if the TU is not to be split (No at S124), then theimage coding apparatus 100 codes cbf_luma (S125). Next, the image codingapparatus 100 determines whether or not the prediction method used forthe TU (CU) is inter prediction (S126). If inter prediction is not used(for example, if intra prediction is adopted) (No at S126), then theimage coding apparatus 100 codes cbf_chroma (S127). The processing fromStep S132 is the same as the processing in FIG. 11.

As described above, in the image coding method according to the presentembodiment, if inter prediction is adopted for a current CU, thencbf_chroma at the highest level of hierarchy is coded, and if the intraprediction is adopted, cbf_chroma at a leaf node is coded.

Here, inter prediction is unlikely to cause a transform coefficient. Inparticular, inter prediction is unlikely to cause a transformcoefficient of chrominance signal. Therefore, if inter prediction isadopted, coding of cbf_chroma prior to TU splitting is more efficientthan coding of cbf_chroma after TU splitting. On the other hand, intraprediction is likely to cause a transform coefficient. Therefore, codingprior to TU splitting produces little improvement of a codingefficiency. Therefore, the image coding apparatus 100 codes cbf_chromaat leaf nodes after TU splitting.

Thus, the image coding apparatus 100 according to the present embodimentcan reduce a data amount of CBFs.

Note that, in the flow described with reference to FIG. 15, if “coding”is replaced by “decoding”, a flow of decoding performed by the imagedecoding apparatus 200 can be obtained.

(Embodiment 4)

Embodiment 4 is a variation of the above-described Embodiment 3.

FIG. 16 is a flowchart of coding according to the present embodiment.The same reference numerals in FIG. 15 are assigned to the identicalsteps in FIG. 16, and therefore differences between FIG. 15 and FIG. 16are mainly described.

As described in Embodiment 3, a tendency of having a transformcoefficient and the like heavily depends on whether a prediction methodis inter prediction or non-inter prediction (intra prediction). Inparticular, if intra prediction is adopted, a great number of intrapredictions and transforms are necessary for small blocks. In order toaddress this, decrease of steps in intra prediction is particularlyimportant. Therefore, according to the present embodiment, processing isselected at an upper level of hierarchy based on whether a predictionmethod is inter prediction or intra prediction (non-inter prediction).As a result, the processing in the case of inter prediction is separatedfrom the processing in the case of intra prediction. Thereby, it is easyto optimize implementation.

More specifically, as shown in FIG. 16, at the leaf nodes, cbf_luma iscoded after the determination (S126) as to whether the prediction methodis inter prediction or non-inter prediction. More specifically, if interprediction is not adopted (No at S126), then the image coding apparatus100 codes cbf_luma (S125B), and codes cbf_chroma (S127). On the otherhand, if inter prediction is adopted (Yes at S127), then the imagecoding apparatus 100 codes cbf_luma (S125A). The processing from StepS132 is the same as the processing in FIG. 11.

The processing for CBF is likely to be complicated with the case whereflags are eliminated. On the other hand, if processing for CBF isswitched depending on whether a prediction method is inter prediction orintra prediction as described above, the same effects as described abovecan be produced.

As shown in FIG. 17, it is also possible that, if intra prediction isadopted (No at S126), then the image coding apparatus 100 codescbf_chroma (S127), and then codes cbf_luma (S125B). Thereby, an order ofcoding cbf_chroma and cbf_luma is the same between the case using interprediction (S123, S125A) and the case using inter prediction (S127 andS125B). As described above, communalizing the processing order canreduce a data amount of a processing program.

Note that, in the flow described with reference to FIGS. 16 and 17, if“coding” is replaced by “decoding”, a flow of decoding performed by theimage decoding apparatus 200 can be obtained.

(Embodiment 5)

In Embodiment 5, an order of coding CBFs and transform coefficients isdescribed.

Each of FIGS. 18A to 18C shows an order of coding CBFs and transformcoefficients (BlockCoeff). In other words, each of FIGS. 18A to 18Cshows an arrangement of CBFs and transform coefficients in a codedsignal 191. In FIGS. 18A to 18C, each numeral value indicates a codingorder. In each of FIGS. 18A to 18C, the number of transform blocks ofluma (luminance signal) is equal to the number of transform blocks ofchroma (chrominance signal).

The coding order shown in FIG. 18A is, for instance, one example of thecoding order according to Embodiment 1. In FIG. 18A, cbf_luma (Blk=0),cbf_cb (Blk=0), and cbf_cr (Blk=0) are coded in order, and then cbf_luma(Blk=1), cbf_cb (Blk=1), cbf_cr (Blk=1), cbf_luma (Blk=2), cbf_cb(Blk=2), cbf_cr (Blk=2), cbf_luma (Blk=3), cbf_cb (Blk=3), cbf_cr(Blk=3) are coded in order. Here, each Blk value indicates a spatialposition of a corresponding block in a Z order. Blk=0 indicates a blockat the upper left, Blk=1 indicates a block at the upper right, Blk=2indicates a block at the lower left, and Blk=3 indicates a block at thelower right.

Subsequent to coding all of the CBFs, BlockCoeff (luma, Blk=0),BlockCoeff (cb, Blk=0), and BlockCoeff (cr, Blk=0) are coded in order.Next, BlockCoeff (luma, Blk=1), BlockCoeff (cb, Blk=1), and BlockCoeff(cr, Blk=1) are coded in order.

The coding order shown in FIG. 18B is, for instance, one example of thecoding order according to Embodiments 2 to 4. CBFs and transformcoefficients are coded in the same tree structure. Therefore, atransform coefficient at a certain position is coded relativelyimmediately after coding a corresponding CBF.

For example, first, cbf_luma (blk=0), cbf_cb (blk=0), and cbf_cr (blk=0)are coded in order, and after that, BlockCoeff (luma, Blk=0), BlockCoeff(cb, Blk=0), and BlockCoeff (cr, Blk=0), which correspond to the aboveCBFs respectively, are coded in order. Thereby, the image decodingapparatus 200 can reduce a memory size for temporarily storing the CBFflags. In the image coding apparatus 100, BlockCoeff cannot be stored ina stream until CBFs of all blocks are determined. Therefore, there is aproblem that a memory size is large enough to store all BlockCoeff ofblocks prior to a current block in the block order. This problem isreduced by using the processing order shown in FIG. 18B.

In FIG. 18C, immediately after coding a CBF flag, a correspondingtransform coefficient is coded. In this example, a size of a memory fortemporarily storing CBFs and transform coefficients is further reducedin comparison to the case shown in FIG. 18B. More specifically, cbf_luma(blk=0), BlockCoeff (luma, Blk=0), cbf_cb (blk=0), BlockCoeff (cb,Blk=0), cbf_cr (blk=0), BlockCoeff (cr, Blk=0), . . . are coded inorder.

Next, the description is given for a coding order in the case where thenumber of transform blocks of chrominance signal is less than the numberof transform blocks of luminance signal. Each of FIGS. 19A and 19B showsan example of the coding order in the above case.

For example, at a 4:2:0 format, the number of pixels of chrominancesignal is a half of the number of pixels of luminance signal, in a viewof a horizontal or vertical line of pixels. For the transform size or aninverse transform size, a minimum size (MinTrafoSize) is defined. Morespecifically, in the minimum size (Transform Size=MinTrafoSize), thereis a case where four TUs can be used for luminance signal, but only oneTU is allowed for chrominance signal.

In FIG. 19A, a transform coefficient is coded immediately after coding aCBF. Blocks are sequentially coded in an order of having a smallerBlkIdx. The coding order has advantages of reducing a size of atemporary memory because a CBF and a corresponding transform coefficientare close to each other in the coding order.

In FIG. 19B, first, CBFs and transform coefficients of luminance signalare coded, and then CBFs and transform coefficients of chrominancesignal are coded. This coding method has advantages of minimizingprocesses between luminance signal and chrominance signal and alsominimizing switch processes of a data input/output pointer. Predictionprocessing and data storing destination are sometimes considerablydifferent between luminance signal and chrominance signal. Therefore, itis desirable to continuously perform processes for blocks of luminancesignal, and then continuously perform processes for blocks ofchrominance signal. Here, the blocks of chrominance signal are codedafter coding all of the blocks of luminance signal. However, the sameeffects can be produced also when the blocks of chrominance signal arecoded before coding all of the blocks of luminance signal.

In FIG. 19B, cbf_luma (upper left), BlockCoeff_luma (upper left),cbf_luma (upper right), BlockCoeff_luma (upper right), cbf_luma (lowerleft), BlockCoeff_luma (lower left), cbf_luma (lower right),BlockCoeff_luma (lower right), cbf_cb, BlockCoeff_cb, cbf_cr, andBlockCoeff_cr are coded in order.

FIG. 20 is a flowchart of coding according to the present embodiment.FIG. 20 shows only the processing for CBFs and transform coefficientswhich is a part of the coding. Here, four split blocks are associatedwith respective BlkIdx in a Z order.

The series of Steps S125 to S152 in FIG. 20 are processing for codingCBF. The series of Steps S125 to S123B are performed on each of the foursplit blocks.

For a certain block, the image coding apparatus 100 codes cbf_luma(S125). Next, the image coding apparatus 100 determines whether or notthe number of blocks of luminance signal is equal to the number ofblocks of chrominance signal. In addition, the image coding apparatus100 determines whether or not Blkidx=3 (S151). In other words, it isdetermined whether or not a current TU is a last TU of the four splitTUs in the coding order. If the number of blocks of luminance signal isequal to the number of blocks of chrominance signal, or if Blkidx=3 (Yesat S151), then the image coding apparatus 100 codes cbf_cb and cbf_cr(S123A and S123B). For example, if TrafoSize that is a size of luminancesignal block at a current TrD does not reach the minimum sizeMinTrafoSize (TrafoSize>MinTrafoSize), then it is determined that thenumber of blocks of luminance signal is equal to the number of blocks ofchrominance signal. It is also possible that the image coding apparatus100 uses a different method to determine whether or not the number ofblocks of luminance signal is equal to the number of blocks ofchrominance signal.

Even if blocks of luminance signal is less than blocks of chrominancesignal, the image coding apparatus 100 codes cbf_chroma after coding allof cbf_luma. In other words, in the case of splitting to four blocks,coding of cbf_luma of the four blocks have been completed when Blkidx=3.Therefore, the image coding apparatus 100 determines that cbf_chroma isto be performed when Blkidx=3.

In summary, the image coding apparatus 100 codes cbf_chroma after codingcbf_luma when (Trafosize>MinTrafoSize)∥(Blkidx==3).

On the other hand, if Blkidx is not 3 (No at S152), then a next block isselected to perform the processing from Step S125.

The series of Steps S132 to S154 in FIG. 20 are processing for coding atransform coefficient. The series of Steps S132 to S135B are performedon each of four split blocks in the same manner as the CBF coding.

The image coding apparatus 100 determines whether or not cbf_luma istrue (S132). If cbf_luma is true (Yes at S132), then the image codingapparatus 100 codes a transform coefficient of luminance signal of acurrent TU (S133). Next, the image coding apparatus 100 performs thesame determination as Step S151 (S153).

If the determination is made as true (Yes at S153), then the imagecoding apparatus 100 determines whether cbf_cb is true (S134A). Ifcbf_cb is true (Yes at S134A), then the image coding apparatus 100 codesa transform coefficient of chrominance Cb (S135A). The image codingapparatus 100 determines whether or not cbf_cr is true (S134B). Ifcbf_cr is true (Yes at S134B), then the image coding apparatus 100 codesa transform coefficient of chrominance Cr (S135B).

Note that, in the flow described with reference to FIG. 20, if “coding”is replaced by “decoding”, a flow of decoding performed by the imagedecoding apparatus 200 can be obtained. Furthermore, in the codingorders described with reference to FIG. 18A to 18C, FIGS. 19A and 19B,if “coding” is replaced by “decoding”, a decoding order of decodingcoded pieces of data can be obtained.

Each of FIGS. 21A and 21B shows an example where CBFs and transformcoefficients of chrominance signal are coded prior to CBFs and transformcoefficients of luminance signal. As described above, in interprediction, cbf_chroma is sometimes coded before cbf_luma. Therefore, ifblocks of chrominance signal are coded earlier, it is possible to causean order of processing cbf_chroma and cbf_luma to be the same betweeninter prediction and intra prediction. As a result, it is possible tosimplify the flows of the processing performed by the image codingapparatus 100 and the image decoding apparatus 200.

(Embodiment 6)

Embodiment 6 is a variation of the above-described Embodiment 3. In theimage coding method according to the present embodiment, a differencequantization parameter (ΔQP) is coded. ΔQP is information indicating adifference between a quantization step used in immediately-priorquantization and a quantization step used in quantization of a currenttransform unit.

Each of FIGS. 22A and 22B is a flowchart of coding according to thepresent embodiment. The following describes mainly differences from FIG.15.

ΔQP is coded after coding all CBFs. More specifically, the image codingapparatus 100 codes ΔQP after coding cbf_chroma (S123 or S127) andcoding cbf_luma (S125), and before coding a transform coefficient (S133and S135) (S161).

As described above, the image coding apparatus 100 codes ΔQP at acurrent leaf node in a tree structure, and arranges the coded ΔQP at aposition corresponding to the current leaf node of the coded signal 191.Furthermore, at the leaf node, the image decoding apparatus 200 decodesthe coded ΔQP which is arranged at the position corresponding to theleaf node in the tree structure of the coded signal 191.

Here, the image decoding apparatus 200 may decode a transformcoefficient, and immediately at the same perform inverse quantizationimmediately, by using pipeline parallel processing. In this case, thecoding of ΔQP in the above-described coding order to determine aquantization parameter does not occur unnecessary delay or memoryincrease.

In a certain coding unit CU, ΔQP is coded only once in a TU wherecbf_luma and cbf_chroma are first true. If ΔQP is updated more often, acoding amount is increased too much.

FIG. 22B is a flowchart of a coding method in the case where ΔQP iscoded at a root of the tree structure of TUs. As shown in FIG. 22B, theimage coding apparatus 100 codes the root of the tree structure of TUs(S161).

As described above, the image coding apparatus 100 codes ΔQP at a rootof the tree structure, and arranges the coded difference quantizationstep at a position corresponding to the root of the coded signal 191. Inaddition, the image decoding apparatus 200 decodes, at the root, thecoded difference quantization step that is arranged at the position atthe root of the tree structure of the coded signal 191.

In this case, the image decoding apparatus 200 can determine, at anearlier stage, a quantization parameter required by the inversequantization unit 240. Therefore, the image decoding apparatus 200 canperform activation of the inverse quantization unit 240 early. The imagecoding apparatus 100 does not code ΔQP always. ΔQP is coded only whenno_reisidual_data is true for each coding unit CU. As a result, a dataamount can be reduced. no_residual_data is a flag indicating that thereis no transform coefficient in a current CU. This no_residual_data iscoded prior to the first TUS in a current CU.

Note that, in the flow described with reference to FIGS. 22A and 22B, if“coding” is replaced by “decoding”, a flow of decoding performed by theimage decoding apparatus 200 can be obtained.

Each of FIGS. 23 and 24A to 24C shows an example of syntax of HEVCcorresponding to Embodiment 6.

(Embodiment 7)

Embodiment 7 is a variation of the above-described Embodiment 3.

Each of FIGS. 25A and 25B is a flowchart of coding performed by theimage coding apparatus 100 according to the present embodiment.

In the coding in FIGS. 25A and 25B, the coding of a transformcoefficient shown in FIG. 15 (S132 to S135) is extracted as unifiedtransform (transform_unified_unit) (S171) that is one of subroutines. Inthe same manner as described in the previous embodiments, the presentembodiment also produces effects of reducing an amount of a memory fortemporarily storing information of CBFs and TUSs, simplifying steps inthe processing, and decreasing the number of traverses. It is alsopossible that the series of Steps S125 to S127 are included in theunified transform. In this case, the subroutine corresponds to theprocessing for a leaf node in the tree structure of TUs. Furthermore,ΔQP may be coded in the unified transform. In addition to thesubstantially same effects, the provision of the subroutine can producefurther effects of power saving in design by separating the steps andtest reduction.

Although only some exemplary embodiments of the image coding apparatusand the image decoding apparatus according to the present invention havebeen described in detail above, the present invention is not limited tothese embodiments.

Note also that processing units in each of the image coding apparatusand the image decoding apparatus according to the above embodiments aretypically implemented into a Large Scale Integration (LSI) which is anintegrated circuit. These may be integrated separately, or a part or allof them may be integrated into a single chip.

Note also that the technique of integrated circuit is not limited to theLSI, and it may be implemented as a dedicated circuit or ageneral-purpose processor. It is also possible to use a FieldProgrammable Gate Array (FPGA) that can be programmed aftermanufacturing the LSI, or a reconfigurable processor in which connectionand setting of circuit cells inside the LSI can be reconfigured.

Note also that each of the structural elements in the above embodimentsmay be implemented by a dedicated hardware, or implemented by executinga software program suitable for the structural element. Each of thestructural elements may be implemented when a program execution unitsuch as a CPU or a processor reads a software program recorded on arecording medium such as a hard disk or a semiconductor memory andexecutes the readout software program.

Furthermore, the prevent invention may be software program, or may be anon-transitory computer-readable recording medium on which the programis recorded. Of course, the above-described program may be distributedvia a transmission medium such as the Internet.

Furthermore, the numerals in the above description are examples forexplaining the present disclosure in more detail. The present discloseris not limited to the example numerals.

Moreover, the splitting of the functional blocks in the block diagramsare examples. It is also possible that a plurality of functional blocksare implemented as one functional block, that one functional block issplit into a plurality of pieces, or that shifts a partial function toother functional blocks. In addition, the functions of the plurality offunctional blocks having similar functions may be performed in parallelor in time sharing by a common single hardware or software.

The order of executing the steps included in each of the above-describedimage coding method and the above-described image decoding method is theexample of explaining the present disclosure in more detail. Therefore,different orders except the above-described order may be used. A part ofthe steps may be executed at the same time (in parallel) with othersteps.

Thus, although only some exemplary embodiments of the image codingapparatus and the image decoding apparatus according to the presentinvention have been described in detail above, the present invention isnot limited to these embodiments. Those skilled in the art will bereadily appreciated that various modifications of the exemplaryembodiments and combinations of the structural elements of the differentembodiments are possible without materially departing from the novelteachings and advantages of the present disclosure. Accordingly, allsuch modifications and combinations are intended to be included withinthe scope of the present disclosure.

(Embodiment 8)

The processing described in each of Embodiments can be simplyimplemented in an independent computer system, by recording, in arecording medium, a program for implementing the configurations of themoving picture coding method (image coding method) and the movingpicture decoding method (image decoding method) described in each ofEmbodiments. The recording media may be any recording media as long asthe program can be recorded, such as a magnetic disk, an optical disk, amagnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the moving picture coding method (imagecoding method) and the moving picture decoding method (image decodingmethod) described in each of Embodiments and systems using thereof willbe described. The system has a feature of having an image coding anddecoding apparatus that includes an image encoding apparatus using theimage encoding method and an image decoding apparatus using the imagedecoding method. Other configurations in the system can be changed asappropriate depending on the cases.

FIG. 26 illustrates an overall configuration of a content providingsystem ex100 for implementing content distribution services. The areafor providing communication services is divided into cells of desiredsize, and base stations ex106, ex107, ex108, ex109, and ex110 which arefixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as acomputer ex111, a personal digital assistant (PDA) ex112, a cameraex113, a cellular phone ex114 and a game machine ex115, via the Internetex101, an Internet service provider ex102, a telephone network ex104, aswell as the base stations ex106 to ex110, respectively.

However, the configuration of the content providing system ex100 is notlimited to the configuration shown in FIG. 26, and a combination inwhich any of the elements are connected is acceptable. In addition, eachdevice may be directly connected to the telephone network ex104, ratherthan via the base stations ex106 to ex110 which are the fixed wirelessstations. Furthermore, the devices may be interconnected to each othervia a short distance wireless communication and others.

The camera ex113, such as a digital video camera, is capable ofcapturing video. A camera ex116, such as a digital video camera, iscapable of capturing both still images and video. Furthermore, thecellular phone ex114 may be the one that meets any of the standards suchas Global System for Mobile Communications (GSM), Code Division MultipleAccess (CDMA), Wideband-Code Division Multiple Access (W-CDMA), LongTerm Evolution (LTE), and High Speed Packet Access (HSPA).Alternatively, the cellular phone ex114 may be a Personal HandyphoneSystem (PHS).

In the content providing system ex100, a streaming server ex103 isconnected to the camera ex113 and others via the telephone network ex104and the base station ex109, which enables distribution of images of alive show and others. In such a distribution, a content (for example,video of a music live show) captured by the user using the camera ex113is coded as described above in each of Embodiments (i.e., the camerafunctions as the image coding apparatus of the present disclosure), andthe coded content is transmitted to the streaming server ex103. On theother hand, the streaming server ex103 carries out stream distributionof the transmitted content data to the clients upon their requests. Theclients include the computer ex111, the PDA ex112, the camera ex113, thecellular phone ex114, and the game machine ex115 that are capable ofdecoding the above-mentioned coded data. Each of the devices that havereceived the distributed data decodes and reproduces the coded data(i.e., the devices each function as the image decoding apparatus of thepresent disclosure).

The captured data may be coded by the camera ex113 or the streamingserver ex103 that transmits the data, or the coding processes may beshared between the camera ex113 and the streaming server ex103.Similarly, the distributed data may be decoded by the clients or thestreaming server ex103, or the decoding processes may be shared betweenthe clients and the streaming server ex103. Furthermore, the data of thestill images and video captured by not only the camera ex113 but alsothe camera ex116 may be transmitted to the streaming server ex103through the computer ex111. The coding processes may be performed by thecamera ex116, the computer ex111, or the streaming server ex103, orshared among them.

Furthermore, the coding and decoding processes may be performed by anLSI ex500 generally included in each of the computer ex111 and thedevices. The LSI ex500 may be configured of a single chip or a pluralityof chips. Software for coding and decoding video may be integrated intosome type of a recording medium (such as a CD-ROM, a flexible disk, anda hard disk) that is readable by the computer ex111 and others, and thecoding and decoding processes may be performed using the software.Furthermore, when the cellular phone ex114 is equipped with a camera,the image data obtained by the camera may be transmitted. The video datais data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers andcomputers, and may decentralize data and process the decentralized data,record, or distribute data.

As described above, the clients may receive and reproduce the coded datain the content providing system ex100. In other words, the clients canreceive and decode information transmitted by the user, and reproducethe decoded data in real time in the content providing system ex100, sothat the user who does not have any particular right and equipment canimplement personal broadcasting.

Aside from the example of the content providing system ex100, at leastone of the moving picture coding apparatus (image coding apparatus) andthe moving picture decoding apparatus (image decoding apparatus)described in each of Embodiments may be implemented in a digitalbroadcasting system ex200 illustrated in FIG. 27. More specifically, abroadcast station ex201 communicates or transmits, via radio waves to abroadcast satellite ex202, multiplexed data obtained by multiplexingaudio data and others onto video data. The video data is data coded bythe moving picture coding method described in each of Embodiments (i.e.,data coded by the image coding apparatus of the present disclosure).Upon receipt of the multiplexed data, the broadcast satellite ex202transmits radio waves for broadcasting. Then, a home-use antenna ex204with a satellite broadcast reception function receives the radio waves.Next, a device such as a television (receiver) ex300 and a set top box(STB) ex217 decodes the received multiplexed data, and reproduces thedecoded data (i.e., the device functions as the image coding apparatusof the present disclosure).

Furthermore, a reader/recorder ex218 (i) reads and decodes themultiplexed data recorded on a recording media ex215, such as a DVD anda BD, or (i) codes video signals in the recording medium ex215, and insome cases, writes data obtained by multiplexing an audio signal on thecoded data. The reader/recorder ex218 can include the moving picturedecoding apparatus or the moving picture coding apparatus as shown ineach of Embodiments. In this case, the reproduced video signals aredisplayed on the monitor ex219, and can be reproduced by another deviceor system using the recording medium ex215 on which the multiplexed datais recorded. It is also possible to implement the moving picturedecoding apparatus in the set top box ex217 connected to the cable ex203for a cable television or to the antenna ex204 for satellite and/orterrestrial broadcasting, so as to display the video signals on themonitor ex219 of the television ex300. The moving picture decodingapparatus may be implemented not in the set top box but in thetelevision ex300.

FIG. 28 illustrates the television (receiver) ex300 that uses the movingpicture coding method and the moving picture decoding method describedin each of Embodiments. The television ex300 includes: a tuner ex301that obtains or provides multiplexed data obtained by multiplexing audiodata onto video data, through the antenna ex204 or the cable ex203, etc.that receives a broadcast; a modulation/demodulation unit ex302 thatdemodulates the received multiplexed data or modulates data intomultiplexed data to be supplied outside; and amultiplexing/demultiplexing unit ex303 that demultiplexes the modulatedmultiplexed data into video data and audio data, or multiplexes videodata and audio data coded by a signal processing unit ex306 into data.

The television ex300 further includes: a signal processing unit ex306including an audio signal processing unit ex304 and a video signalprocessing unit ex305 that decode audio data and video data and codeaudio data and video data, (which function as the image coding apparatusand the image decoding apparatus), respectively; and an output unitex309 including a speaker ex307 that provides the decoded audio signal,and a display unit ex308 that displays the decoded video signal, such asa display. Furthermore, the television ex300 includes an interface unitex317 including an operation input unit ex312 that receives an input ofa user operation. Furthermore, the television ex300 includes a controlunit ex310 that controls overall each constituent element of thetelevision ex300, and a power supply circuit unit ex311 that suppliespower to each of the elements. Other than the operation input unitex312, the interface unit ex317 may include: a bridge ex313 that isconnected to an external device, such as the reader/recorder ex218; aslot unit ex314 for enabling attachment of the recording medium ex216,such as an SD card; a driver ex315 to be connected to an externalrecording medium, such as a hard disk; and a modem ex316 to be connectedto a telephone network. Here, the recording medium ex216 canelectrically record information using a non-volatile/volatilesemiconductor memory element for storage. The constituent elements ofthe television ex300 are connected to each other through a synchronousbus.

First, the configuration in which the television ex300 decodesmultiplexed data obtained from outside through the antenna ex204 andothers and reproduces the decoded data will be described. In thetelevision ex300, upon a user operation through a remote controllerex220 and others, the multiplexing/demultiplexing unit ex303demultiplexes the multiplexed data demodulated by themodulation/demodulation unit ex302, under control of the control unitex310 including a CPU. Furthermore, the audio signal processing unitex304 decodes the demultiplexed audio data, and the video signalprocessing unit ex305 decodes the demultiplexed video data, using thedecoding method described in each of Embodiments, in the televisionex300. The output unit ex309 provides the decoded video signal and audiosignal outside, respectively. When the output unit ex309 provides thevideo signal and the audio signal, the signals may be temporarily storedin buffers ex318 and ex319, and others so that the signals arereproduced in synchronization with each other. Furthermore, thetelevision ex300 may read multiplexed data not through a broadcast andothers but from the recording media ex215 and ex216, such as a magneticdisk, an optical disk, and a SD card. Next, a configuration in which thetelevision ex300 codes an audio signal and a video signal, and transmitsthe data outside or writes the data on a recording medium will bedescribed. In the television ex300, upon a user operation through theremote controller ex220 and others, the audio signal processing unitex304 codes an audio signal, and the video signal processing unit ex305codes a video signal, under control of the control unit ex310 using thecoding method described in each of Embodiments. Themultiplexing/demultiplexing unit ex303 multiplexes the coded videosignal and audio signal, and provides the resulting signal outside. Whenthe multiplexing/demultiplexing unit ex303 multiplexes the video signaland the audio signal, the signals may be temporarily stored in thebuffers ex320 and ex321, and others so that the signals are reproducedin synchronization with each other. Here, the buffers ex318, ex319,ex320, and ex321 may be plural as illustrated, or at least one buffermay be shared in the television ex300. Furthermore, data may be storedin a buffer so that the system overflow and underflow may be avoidedbetween the modulation/demodulation unit ex302 and themultiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration forreceiving an AV input from a microphone or a camera other than theconfiguration for obtaining audio and video data from a broadcast or arecording medium, and may code the obtained data. Although thetelevision ex300 can code, multiplex, and provide outside data in thedescription, it may be capable of only receiving, decoding, andproviding outside data but not the coding, multiplexing, and providingoutside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexeddata from or on a recording medium, one of the television ex300 and thereader/recorder ex218 may decode or code the multiplexed data, and thetelevision ex300 and the reader/recorder ex218 may share the decoding orcoding.

As an example, FIG. 29 illustrates a configuration of an informationreproducing/recording unit ex400 when data is read or written from or onan optical disk. The information reproducing/recording unit ex400includes constituent elements ex401, ex402, ex403, ex404, ex405, ex406,and ex407 to be described hereinafter. The optical head ex401 irradiatesa laser spot in a recording surface of the recording medium ex215 thatis an optical disk to write information, and detects reflected lightfrom the recording surface of the recording medium ex215 to read theinformation. The modulation recording unit ex402 electrically drives asemiconductor laser included in the optical head ex401, and modulatesthe laser light according to recorded data. The reproductiondemodulating unit ex403 amplifies a reproduction signal obtained byelectrically detecting the reflected light from the recording surfaceusing a photo detector included in the optical head ex401, anddemodulates the reproduction signal by separating a signal componentrecorded on the recording medium ex215 to reproduce the necessaryinformation. The buffer ex404 temporarily holds the information to berecorded on the recording medium ex215 and the information reproducedfrom the recording medium ex215. The disk motor ex405 rotates therecording medium ex215. The servo control unit ex406 moves the opticalhead ex401 to a predetermined information track while controlling therotation drive of the disk motor ex405 so as to follow the laser spot.The system control unit ex407 controls overall the informationreproducing/recording unit ex400. The reading and writing processes canbe implemented by the system control unit ex407 using variousinformation stored in the buffer ex404 and generating and adding newinformation as necessary, and by the modulation recording unit ex402,the reproduction demodulating unit ex403, and the servo control unitex406 that record and reproduce information through the optical headex401 while being operated in a coordinated manner. The system controlunit ex407 includes, for example, a microprocessor, and executesprocessing by causing a computer to execute a program for read andwrite.

Although the optical head ex401 irradiates a laser spot in thedescription, it may perform high-density recording using near fieldlight.

FIG. 30 illustrates the recording medium ex215 that is the optical disk.On the recording surface of the recording medium ex215, guide groovesare spirally formed, and an information track ex230 records, in advance,address information indicating an absolute position on the diskaccording to change in a shape of the guide grooves. The addressinformation includes information for determining positions of recordingblocks ex231 that are a unit for recording data. Reproducing theinformation track ex230 and reading the address information in anapparatus that records and reproduces data can lead to determination ofthe positions of the recording blocks. Furthermore, the recording mediumex215 includes a data recording area ex233, an inner circumference areaex232, and an outer circumference area ex234. The data recording areaex233 is an area for use in recording the user data. The innercircumference area ex232 and the outer circumference area ex234 that areinside and outside of the data recording area ex233, respectively arefor specific use except for recording the user data. The informationreproducing/recording unit 400 reads and writes coded audio, coded videodata, or multiplexed data obtained by multiplexing the coded audio andvideo data, from and on the data recording area ex233 of the recordingmedium ex215.

Although an optical disk having a layer, such as a DVD and a BD isdescribed as an example in the description, the optical disk is notlimited to such, and may be an optical disk having a multilayerstructure and capable of being recorded on a part other than thesurface. Furthermore, the optical disk may have a structure formultidimensional recording/reproduction, such as recording ofinformation using light of colors with different wavelengths in the sameportion of the optical disk and for recording information havingdifferent layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data fromthe satellite ex202 and others, and reproduce video on a display devicesuch as a car navigation system ex211 set in the car ex210, in thedigital broadcasting system ex200. Here, a configuration of the carnavigation system ex211 will be a configuration, for example, includinga GPS receiving unit from the configuration illustrated in FIG. 28. Thesame will be true for the configuration of the computer ex111, thecellular phone ex114, and others.

FIG. 31A illustrates the cellular phone ex114 that uses the movingpicture coding method and the moving picture decoding method describedin Embodiments. The cellular phone ex114 includes: an antenna ex350 fortransmitting and receiving radio waves through the base station ex110; acamera unit ex365 capable of capturing moving and still images; and adisplay unit ex358 such as a liquid crystal display for displaying thedata such as decoded video captured by the camera unit ex365 or receivedby the antenna ex350. The cellular phone ex114 further includes: a mainbody unit including an operation key unit ex366; an audio output unitex357 such as a speaker for output of audio; an audio input unit ex356such as a microphone for input of audio; a memory unit ex367 for storingcaptured video or still pictures, recorded audio, coded or decoded dataof the received video, the still pictures, e-mails, or others; and aslot unit ex364 that is an interface unit for a recording medium thatstores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex114 will bedescribed with reference to FIG. 31B. In the cellular phone ex114, amain control unit ex360 designed to control overall each unit of themain body including the display unit ex358 as well as the operation keyunit ex366 is connected mutually, via a synchronous bus ex370, to apower supply circuit unit ex361, an operation input control unit ex362,a video signal processing unit ex355, a camera interface unit ex363, aliquid crystal display (LCD) control unit ex359, amodulation/demodulation unit ex352, a multiplexing/demultiplexing unitex353, an audio signal processing unit ex354, the slot unit ex364, andthe memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation,the power supply circuit unit ex361 supplies the respective units withpower from a battery pack so as to activate the cell phone ex114.

In the cellular phone ex114, the audio signal processing unit ex354converts the audio signals collected by the audio input unit ex356 invoice conversation mode into digital audio signals under the control ofthe main control unit ex360 including a CPU, ROM, and RAM. Then, themodulation/demodulation unit ex352 performs spread spectrum processingon the digital audio signals, and the transmitting and receiving unitex351 performs digital-to-analog conversion and frequency conversion onthe data, so as to transmit the resulting data via the antenna ex350.Also, in the cellular phone ex114, the transmitting and receiving unitex351 amplifies the data received by the antenna ex350 in voiceconversation mode and performs frequency conversion and theanalog-to-digital conversion on the data. Then, themodulation/demodulation unit ex352 performs inverse spread spectrumprocessing on the data, and the audio signal processing unit ex354converts it into analog audio signals, so as to output them via theaudio output unit ex357.

Furthermore, when an e-mail in data communication mode is transmitted,text data of the e-mail inputted by operating the operation key unitex366 and others of the main body is sent out to the main control unitex360 via the operation input control unit ex362. The main control unitex360 causes the modulation/demodulation unit ex352 to perform spreadspectrum processing on the text data, and the transmitting and receivingunit ex351 performs the digital-to-analog conversion and the frequencyconversion on the resulting data to transmit the data to the basestation ex110 via the antenna ex350. When an e-mail is received,processing that is approximately inverse to the processing fortransmitting an e-mail is performed on the received data, and theresulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication modeis or are transmitted, the video signal processing unit ex355 compressesand codes video signals supplied from the camera unit ex365 using themoving picture coding method shown in each of Embodiments (i.e.,functions as the image coding apparatus of the present disclosure), andtransmits the coded video data to the multiplexing/demultiplexing unitex353. In contrast, during when the camera unit ex365 captures video,still images, and others, the audio signal processing unit ex354 codesaudio signals collected by the audio input unit ex356, and transmits thecoded audio data to the multiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded videodata supplied from the video signal processing unit ex355 and the codedaudio data supplied from the audio signal processing unit ex354, using apredetermined method. Then, the modulation/demodulation unit(modulation/demodulation circuit unit) ex352 performs spread spectrumprocessing on the multiplexed data, and the transmitting and receivingunit ex351 performs digital-to-analog conversion and frequencyconversion on the data so as to transmit the resulting data via theantenna ex350.

When receiving data of a video file which is linked to a Web page andothers in data communication mode or when receiving an e-mail with videoand/or audio attached, in order to decode the multiplexed data receivedvia the antenna ex350, the multiplexing/demultiplexing unit ex353demultiplexes the multiplexed data into a video data bit stream and anaudio data bit stream, and supplies the video signal processing unitex355 with the coded video data and the audio signal processing unitex354 with the coded audio data, through the synchronous bus ex370. Thevideo signal processing unit ex355 decodes the video signal using amoving picture decoding method corresponding to the moving picturecoding method shown in each of Embodiments (i.e., functions as the imagedecoding apparatus of the present disclosure), and then the display unitex358 displays, for instance, the video and still images included in thevideo file linked to the Web page via the LCD control unit ex359.Furthermore, the audio signal processing unit ex354 decodes the audiosignal, and the audio output unit ex357 provides the audio.

Furthermore, similarly to the television ex300, a terminal such as thecellular phone ex114 probably have 3 types of implementationconfigurations including not only (i) a transmitting and receivingterminal including both a coding apparatus and a decoding apparatus, butalso (ii) a transmitting terminal including only a coding apparatus and(iii) a receiving terminal including only a decoding apparatus. Althoughthe digital broadcasting system ex200 receives and transmits themultiplexed data obtained by multiplexing audio data onto video data inthe description, the multiplexed data may be data obtained bymultiplexing not audio data but character data related to video ontovideo data, and may be not multiplexed data but video data itself.

As such, the moving picture coding method and the moving picturedecoding method in each of Embodiments can be used in any of the devicesand systems described. Thus, the advantages described in each ofEmbodiments can be obtained.

Furthermore, the present disclosure is not limited to Embodiments, andvarious modifications and revisions are possible without departing fromthe scope of the present disclosure.

(Embodiment 9)

Video data can be generated by switching, as necessary, between (i) themoving picture coding method or the moving picture coding apparatusshown in each of Embodiments and (ii) a moving picture coding method ora moving picture coding apparatus in conformity with a differentstandard, such as MPEG-2, MPEG4-AVC, and VC-1.

Here, when a plurality of video data that conforms to the differentstandards is generated and is then decoded, the decoding methods need tobe selected to conform to the different standards. However, since towhich standard each of the plurality of the video data to be decodedconform cannot be detected, there is a problem that an appropriatedecoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexingaudio data and others onto video data has a structure includingidentification information indicating to which standard the video dataconforms. The specific structure of the multiplexed data including thevideo data generated in the moving picture coding method and by themoving picture coding apparatus shown in each of Embodiments will behereinafter described. The multiplexed data is a digital stream in theMPEG2-Transport Stream format.

FIG. 32 illustrates a structure of the multiplexed data. As illustratedin FIG. 32, the multiplexed data can be obtained by multiplexing atleast one of a video stream, an audio stream, a presentation graphicsstream (PG), and an interactive graphics stream. The video streamrepresents primary video and secondary video of a movie, the audiostream (IG) represents a primary audio part and a secondary audio partto be mixed with the primary audio part, and the presentation graphicsstream represents subtitles of the movie. Here, the primary video isnormal video to be displayed on a screen, and the secondary video isvideo to be displayed on a smaller window in the primary video.Furthermore, the interactive graphics stream represents an interactivescreen to be generated by arranging the GUI components on a screen. Thevideo stream is coded in the moving picture coding method or by themoving picture coding apparatus shown in each of Embodiments, or in amoving picture coding method or by a moving picture coding apparatus inconformity with a conventional standard, such as MPEG-2, MPEG4-AVC, andVC-1. The audio stream is coded in accordance with a standard, such asDolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. Forexample, 0x1011 is allocated to the video stream to be used for video ofa movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to0x121F are allocated to the presentation graphics streams, 0x1400 to0x141F are allocated to the interactive graphics streams, 0x1B00 to0x1B1F are allocated to the video streams to be used for secondary videoof the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams tobe used for the secondary video to be mixed with the primary audio.

FIG. 33 schematically illustrates how data is multiplexed. First, avideo stream ex235 composed of video frames and an audio stream ex238composed of audio frames are transformed into a stream of PES packetsex236 and a stream of PES packets ex239, and further into TS packetsex237 and TS packets ex240, respectively. Similarly, data of apresentation graphics stream ex241 and data of an interactive graphicsstream ex244 are transformed into a stream of PES packets ex242 and astream of PES packets ex245, and further into TS packets ex243 and TSpackets ex246, respectively. These TS packets are multiplexed into astream to obtain multiplexed data ex247.

FIG. 34 illustrates how a video stream is stored in a stream of PESpackets in more detail. The first bar in FIG. 34 shows a video framestream in a video stream. The second bar shows the stream of PESpackets. As indicated by arrows denoted as yy1, yy2, yy3, and yy4 inFIG. 34, the video stream is divided into pictures as I pictures, Bpictures, and P pictures each of which is a video presentation unit, andthe pictures are stored in a payload of each of the PES packets. Each ofthe PES packets has a PES header, and the PES header stores aPresentation Time-Stamp (PTS) indicating a display time of the picture,and a Decoding Time-Stamp (DTS) indicating a decoding time of thepicture.

FIG. 35 illustrates a format of TS packets to be finally written on themultiplexed data. Each of the TS packets is a 188-byte fixed lengthpacket including a 4-byte TS header having information, such as a PIDfor identifying a stream and a 184-byte TS payload for storing data. ThePES packets are divided, and stored in the TS payloads, respectively.When a BD ROM is used, each of the TS packets is given a 4-byteTP_Extra_Header, thus resulting in 192-byte source packets. The sourcepackets are written on the multiplexed data. The TP_Extra_Header storesinformation such as an Arrival_Time Stamp (ATS). The ATS shows atransfer start time at which each of the TS packets is to be transferredto a PID filter. The source packets are arranged in the multiplexed dataas shown at the bottom of FIG. 35. The numbers incrementing from thehead of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes notonly streams of audio, video, subtitles and others, but also a ProgramAssociation Table (PAT), a Program Map Table (PMT), and a Program ClockReference (PCR). The PAT shows what a PID in a PMT used in themultiplexed data indicates, and a PID of the PAT itself is registered aszero. The PMT stores PIDs of the streams of video, audio, subtitles andothers included in the multiplexed data, and attribute information ofthe streams corresponding to the PIDs. The PMT also has variousdescriptors relating to the multiplexed data. The descriptors haveinformation such as copy control information showing whether copying ofthe multiplexed data is permitted or not. The PCR stores STC timeinformation corresponding to an ATS showing when the PCR packet istransferred to a decoder, in order to achieve synchronization between anArrival Time Clock (ATC) that is a time axis of ATSs, and an System TimeClock (STC) that is a time axis of PTSs and DTSs.

FIG. 36 illustrates the data structure of the PMT in detail. A PMTheader is disposed at the top of the PMT. The PMT header describes thelength of data included in the PMT and others. A plurality ofdescriptors relating to the multiplexed data is disposed after the PMTheader. Information such as the copy control information is described inthe descriptors. After the descriptors, a plurality of pieces of streaminformation relating to the streams included in the multiplexed data isdisposed. Each piece of stream information includes stream descriptorseach describing information, such as a stream type for identifying acompression codec of a stream, a stream PID, and stream attributeinformation (such as a frame rate or an aspect ratio). The streamdescriptors are equal in number to the number of streams in themultiplexed data.

When the multiplexed data is recorded on a recording medium and others,it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management informationof the multiplexed data as shown in FIG. 37. The multiplexed datainformation files are in one to one correspondence with the multiplexeddata, and each of the files includes multiplexed data information,stream attribute information, and an entry map.

As illustrated in FIG. 37, the multiplexed data includes a system rate,a reproduction start time, and a reproduction end time. The system rateindicates the maximum transfer rate at which a system target decoder tobe described later transfers the multiplexed data to a PID filter. Theintervals of the ATSs included in the multiplexed data are set to nothigher than a system rate. The reproduction start time indicates a PTSin a video frame at the head of the multiplexed data. An interval of oneframe is added to a PTS in a video frame at the end of the multiplexeddata, and the PTS is set to the reproduction end time.

As shown in FIG. 38, a piece of attribute information is registered inthe stream attribute information, for each PID of each stream includedin the multiplexed data. Each piece of attribute information hasdifferent information depending on whether the corresponding stream is avideo stream, an audio stream, a presentation graphics stream, or aninteractive graphics stream. Each piece of video stream attributeinformation carries information including what kind of compression codecis used for compressing the video stream, and the resolution, aspectratio and frame rate of the pieces of picture data that is included inthe video stream. Each piece of audio stream attribute informationcarries information including what kind of compression codec is used forcompressing the audio stream, how many channels are included in theaudio stream, which language the audio stream supports, and how high thesampling frequency is. The video stream attribute information and theaudio stream attribute information are used for initialization of adecoder before the player plays back the information.

In the present embodiment, the multiplexed data to be used is of astream type included in the PMT. Furthermore, when the multiplexed datais recorded on a recording medium, the video stream attributeinformation included in the multiplexed data information is used. Morespecifically, the moving picture coding method or the moving picturecoding apparatus described in each of Embodiments includes a step or aunit for allocating unique information indicating video data generatedby the moving picture coding method or the moving picture codingapparatus in each of Embodiments, to the stream type included in the PMTor the video stream attribute information. With the configuration, thevideo data generated by the moving picture coding method or the movingpicture coding apparatus described in each of Embodiments can bedistinguished from video data that conforms to another standard.

Furthermore, FIG. 39 illustrates steps of the moving picture decodingmethod according to the present embodiment. In Step exS100, the streamtype included in the PMT or the video stream attribute information isobtained from the multiplexed data. Next, in Step exS101, it isdetermined whether or not the stream type or the video stream attributeinformation indicates that the multiplexed data is generated by themoving picture coding method or the moving picture coding apparatus ineach of Embodiments. When it is determined that the stream type or thevideo stream attribute information indicates that the multiplexed datais generated by the moving picture coding method or the moving picturecoding apparatus in each of Embodiments, in Step exS102, decoding isperformed by the moving picture decoding method in each of Embodiments.Furthermore, when the stream type or the video stream attributeinformation indicates conformance to the conventional standards, such asMPEG-2, MPEG4-AVC, and VC-1, in Step exS103, decoding is performed by amoving picture decoding method in conformity with the conventionalstandards.

As such, allocating a new unique value to the stream type or the videostream attribute information enables determination whether or not themoving picture decoding method or the moving picture decoding apparatusthat is described in each of Embodiments can perform decoding. Even whenmultiplexed data that conforms to a different standard, an appropriatedecoding method or apparatus can be selected. Thus, it becomes possibleto decode information without any error. Furthermore, the moving picturecoding method or apparatus, or the moving picture decoding method orapparatus in the present embodiment can be used in the devices andsystems described above.

(Embodiment 10)

Each of the moving picture coding method, the moving picture codingapparatus, the moving picture decoding method, and the moving picturedecoding apparatus in each of Embodiments is typically achieved in theform of an integrated circuit or a Large Scale Integrated (LSI) circuit.As an example of the LSI, FIG. 40 illustrates a configuration of the LSIex500 that is made into one chip. The LSI ex500 includes elements ex501,ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to bedescribed below, and the elements are connected to each other through abus ex510. The power supply circuit unit ex505 is activated by supplyingeach of the elements with power when the power supply circuit unit ex505is turned on.

For example, when coding is performed, the LSI ex500 receives an AVsignal from a microphone ex117, a camera ex113, and others through an AVIO ex509 under control of a control unit ex501 including a CPU ex502, amemory controller ex503, a stream controller ex504, and a drivingfrequency control unit ex512. The received AV signal is temporarilystored in an external memory ex511, such as an SDRAM. Under control ofthe control unit ex501, the stored data is segmented into data portionsaccording to the processing amount and speed to be transmitted to asignal processing unit ex507. Then, the signal processing unit ex507codes an audio signal and/or a video signal. Here, the coding of thevideo signal is the coding described in each of Embodiments.Furthermore, the signal processing unit ex507 sometimes multiplexes thecoded audio data and the coded video data, and a stream IO ex506provides the multiplexed data outside. The provided multiplexed data istransmitted to the base station ex107, or written on the recording mediaex215. When data sets are multiplexed, the data should be temporarilystored in the buffer ex508 so that the data sets are synchronized witheach other.

Although the memory ex511 is an element outside the LSI ex500, it may beincluded in the LSI ex500. The buffer ex508 is not limited to onebuffer, but may be composed of buffers. Furthermore, the LSI ex500 maybe made into one chip or a plurality of chips.

Furthermore, although the control unit ex501 includes the CPU ex502, thememory controller ex503, the stream controller ex504, the drivingfrequency control unit ex512, the configuration of the control unitex501 is not limited to such. For example, the signal processing unitex507 may further include a CPU. Inclusion of another CPU in the signalprocessing unit ex507 can improve the processing speed. Furthermore, asanother example, the CPU ex502 may serve as or be a part of the signalprocessing unit ex507, and, for example, may include an audio signalprocessing unit. In such a case, the control unit ex501 includes thesignal processing unit ex507 or the CPU ex502 including a part of thesignal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI,super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and aspecial circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The functional blocks can be integratedusing such a technology. The possibility is that the present disclosureis applied to biotechnology.

(Embodiment 11)

When video data generated in the moving picture coding method or by themoving picture coding apparatus described in each of Embodiments isdecoded, compared to when video data that conforms to a conventionalstandard, such as MPEG-2, MPEG4-AVC, and VC-1 is decoded, the processingamount probably increases. Thus, the LSI ex500 needs to be set to adriving frequency higher than that of the CPU ex502 to be used whenvideo data in conformity with the conventional standard is decoded.However, when the driving frequency is set higher, there is a problemthat the power consumption increases.

In order to solve the problem, the moving picture decoding apparatus,such as the television ex300 and the LSI ex500 is configured todetermine to which standard the video data conforms, and switch betweenthe driving frequencies according to the determined standard. FIG. 41illustrates a configuration ex800 in the present embodiment. A drivingfrequency switching unit ex803 sets a driving frequency to a higherdriving frequency when video data is generated by the moving picturecoding method or the moving picture coding apparatus described in eachof Embodiments. Then, the driving frequency switching unit ex803instructs a decoding processing unit ex801 that executes the movingpicture decoding method described in each of Embodiments to decode thevideo data. When the video data conforms to the conventional standard,the driving frequency switching unit ex803 sets a driving frequency to alower driving frequency than that of the video data generated by themoving picture coding method or the moving picture coding apparatusdescribed in each of Embodiments. Then, the driving frequency switchingunit ex803 instructs the decoding processing unit ex802 that conforms tothe conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includesthe CPU ex502 and the driving frequency control unit ex512 in FIG. 40.Here, each of the decoding processing unit ex801 that executes themoving picture decoding method described in each of Embodiments and thedecoding processing unit ex802 that conforms to the conventionalstandard corresponds to the signal processing unit ex507 in FIG. 40. TheCPU ex502 determines to which standard the video data conforms. Then,the driving frequency control unit ex512 determines a driving frequencybased on a signal from the CPU ex502. Furthermore, the signal processingunit ex507 decodes the video data based on the signal from the CPUex502. For example, the identification information described inEmbodiment 9 is probably used for identifying the video data. Theidentification information is not limited to the one described inEmbodiment 9 but may be any information as long as the informationindicates to which standard the video data conforms. For example, whenwhich standard video data conforms to can be determined based on anexternal signal for determining that the video data is used for atelevision or a disk, etc., the determination may be made based on suchan external signal. Furthermore, the CPU ex502 selects a drivingfrequency based on, for example, a look-up table in which the standardsof the video data are associated with the driving frequencies as shownin FIG. 43. The driving frequency can be selected by storing the look-uptable in the buffer ex508 and in an internal memory of an LSI, and withreference to the look-up table by the CPU ex502.

FIG. 42 illustrates steps for executing a method in the presentembodiment. First, in Step exS200, the signal processing unit ex507obtains identification information from the multiplexed data. Next, inStep exS201, the CPU ex502 determines whether or not the video data isgenerated by the coding method and the coding apparatus described ineach of Embodiments, based on the identification information. When thevideo data is generated by the moving picture coding method and themoving picture coding apparatus described in each of Embodiments, inStep exS202, the CPU ex502 transmits a signal for setting the drivingfrequency to a higher driving frequency to the driving frequency controlunit ex512. Then, the driving frequency control unit ex512 sets thedriving frequency to the higher driving frequency. On the other hand,when the identification information indicates that the video dataconforms to the conventional standard, such as MPEG-2, MPEG4-AVC, andVC-1, in Step exS203, the CPU ex502 transmits a signal for setting thedriving frequency to a lower driving frequency to the driving frequencycontrol unit ex512. Then, the driving frequency control unit ex512 setsthe driving frequency to the lower driving frequency than that in thecase where the video data is generated by the moving picture codingmethod and the moving picture coding apparatus described in each ofEmbodiment.

Furthermore, along with the switching of the driving frequencies, thepower conservation effect can be improved by changing the voltage to beapplied to the LSI ex500 or an apparatus including the LSI ex500. Forexample, when the driving frequency is set lower, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set to a voltage lower than that in the case where the drivingfrequency is set higher.

Furthermore, when the processing amount for decoding is larger, thedriving frequency may be set higher, and when the processing amount fordecoding is smaller, the driving frequency may be set lower as themethod for setting the driving frequency. Thus, the setting method isnot limited to the ones described above. For example, when theprocessing amount for decoding video data in conformity with MPEG 4-AVCis larger than the processing amount for decoding video data generatedby the moving picture coding method and the moving picture codingapparatus described in each of Embodiments, the driving frequency isprobably set in reverse order to the setting described above.

Furthermore, the method for setting the driving frequency is not limitedto the method for setting the driving frequency lower. For example, whenthe identification information indicates that the video data isgenerated by the moving picture coding method and the moving picturecoding apparatus described in each of Embodiments, the voltage to beapplied to the LSI ex500 or the apparatus including the LSI ex500 isprobably set higher. When the identification information indicates thatthe video data conforms to the conventional standard, such as MPEG-2,MPEG4-AVC, and VC-1, the voltage to be applied to the LSI ex500 or theapparatus including the LSI ex500 is probably set lower. As anotherexample, when the identification information indicates that the videodata is generated by the moving picture coding method and the movingpicture coding apparatus described in each of Embodiments, the drivingof the CPU ex502 does not probably have to be suspended. When theidentification information indicates that the video data conforms to theconventional standard, such as MPEG-2, MPEG4-AVC, and VC-1, the drivingof the CPU ex502 is probably suspended at a given time because the CPUex502 has extra processing capacity. Even when the identificationinformation indicates that the video data is generated by the movingpicture coding method and the moving picture coding apparatus describedin each of Embodiments, in the case where the CPU ex502 has extraprocessing capacity, the driving of the CPU ex502 is probably suspendedat a given time. In such a case, the suspending time is probably setshorter than that in the case where when the identification informationindicates that the video data conforms to the conventional standard,such as MPEG-2, MPEG4-AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switchingbetween the driving frequencies in accordance with the standard to whichthe video data conforms. Furthermore, when the LSI ex500 or theapparatus including the LSI ex500 is driven using a battery, the batterylife can be extended with the power conservation effect.

(Embodiment 12)

There are cases where a plurality of video data that conforms todifferent standards, is provided to the devices and systems, such as atelevision and a mobile phone. In order to enable decoding the pluralityof video data that conforms to the different standards, the signalprocessing unit ex507 of the LSI ex500 needs to conform to the differentstandards. However, the problems of increase in the scale of the circuitof the LSI ex500 and increase in the cost arise with the individual useof the signal processing units ex507 that conform to the respectivestandards.

In order to solve the problem, what is conceived is a configuration inwhich the decoding processing unit for implementing the moving picturedecoding method described in each of Embodiments and the decodingprocessing unit that conforms to the conventional standard, such asMPEG-2, MPEG4-AVC, and VC-1 are partly shared. Ex900 in FIG. 44A showsan example of the configuration. For example, the moving picturedecoding method described in each of Embodiments and the moving picturedecoding method that conforms to MPEG4-AVC have, partly in common, thedetails of processing, such as entropy coding, inverse quantization,deblocking filtering, and motion compensated prediction. The details ofprocessing to be shared probably include use of a decoding processingunit ex902 that conforms to MPEG4-AVC. In contrast, a dedicated decodingprocessing unit ex901 is probably used for other processing unique tothe present disclosure. Since the present disclosure is characterized byentropy decoding processing in particular, for example, the dedicateddecoding processing unit ex901 is used for entropy decoding processing.Otherwise, the decoding processing unit is probably shared for one ofinverse quantization, deblocking filtering, and motion compensation, orall of the processing. The decoding processing unit for implementing themoving picture decoding method described in each of Embodiments may beshared for the processing to be shared, and a dedicated decodingprocessing unit may be used for processing unique to that of MPEG4-AVC.

Furthermore, ex1000 in FIG. 44B shows another example in that processingis partly shared. This example uses a configuration including adedicated decoding processing unit ex1001 that supports the processingunique to the present disclosure, a dedicated decoding processing unitex1002 that supports the processing unique to another conventionalstandard, and a decoding processing unit ex1003 that supports processingto be shared between the moving picture decoding method in the presentdisclosure and the conventional moving picture decoding method. Here,the dedicated decoding processing units ex1001 and ex1002 are notnecessarily specialized for the processing of the present disclosure andthe processing of the conventional standard, respectively, and may bethe ones capable of implementing general processing. Furthermore, theconfiguration of the present embodiment can be implemented by the LSIex500.

As such, reducing the scale of the circuit of an LSI and reducing thecost are possible by sharing the decoding processing unit for theprocessing to be shared between the moving picture decoding method inthe present disclosure and the moving picture decoding method inconformity with the conventional standard.

[Industrial Applicability]

The present disclosure can be applied to image coding methods, imagedecoding methods, image coding apparatuses, and image decodingapparatuses. The present disclosure is also applicable tohigh-resolution information display apparatuses or imaging apparatusessuch as television sets, digital video recorders, in-vehicle navigationsystems, portable phones, digital cameras, and digital camcorders, eachof which includes an image coding apparatus.

The invention claimed is:
 1. An image decoding method, comprising:decoding a coded signal to generate quantization coefficients and piecesof management information, the quantization coefficients eachcorresponding to a corresponding one of transform units, and the piecesof the management information indicating a structure of the transformunits; performing inverse quantization and inverse transform on each ofthe quantization coefficients, eventually generating prediction errorsignals of the respective transform units; and adding at least one ofthe prediction error signals to a prediction signal for each of codingunits each including the transform units, eventually generating decodedsignals for each of the coding units, wherein the quantizationcoefficients and the pieces of the management information have a treestructure, each of the transform units corresponds to a correspondingone of leaf nodes in the tree structure, and the decoding includesdecoding, for each of the leaf nodes, a coded piece of the managementinformation and a coded quantization coefficient which are arranged insuccession in the coded signal for the each of the leaf nodes.
 2. Theimage decoding method according to claim 1, wherein the pieces of themanagement information includes respective pieces of split informationeach of which corresponds to a corresponding one of nodes in the treestructure and indicates whether or not a transform unit corresponding tothe corresponding one of the nodes is to be further split.
 3. The imagedecoding method according to claim 2, wherein the pieces of themanagement information includes respective first flags each of whichcorresponds to at least one of the nodes in the tree structure andindicates whether or not a quantization coefficient corresponding toeach of the at least one of the nodes exists.
 4. The image decodingmethod according to claim 3, wherein in the decoding, it is determinedwhether or not a value of the first flag of a current node at a currentlevel can be identified by at least one of (a) the first flag at a levelupper than the current level and (b) the first flag of a different nodeat the current level, and when it is determined that the value of thefirst flag of the current node can be uniquely identified, the firstflag of the current node is not generated by decoding.
 5. The imagedecoding method according to claim 3, wherein the decoding includesdecoding a difference quantization step at a current leaf node in thecoded signal, the difference quantization step being arranged at aposition corresponding to the current leaf node in the tree structure,and the difference quantization step indicates, in the performing ofinverse quantization and inverse orthogonal transform, a differencebetween a quantization step that has most recently been used and aquantization step that is to be used for a current transform unit. 6.The image decoding method according to claim 3, wherein the decodingincludes decoding a difference quantization step at a root of the treestructure in the coded signal, the difference quantization step beingcoded arranged at a position corresponding to the root, and thedifference quantization step indicates, in the performing of inversequantization and inverse orthogonal transform, a difference between aquantization step that has most recently been used and a quantizationstep that is to be used for a current transform unit.
 7. The imagedecoding method according to claim 3, wherein each of the quantizationcoefficients includes a luminance quantization coefficient and achrominance quantization coefficient, and the first flag includes asecond flag and a third flag, the second flag indicating whether or notthe luminance quantization coefficient exists, and the third flagindicating whether or not the chrominance quantization coefficientexists, in the coded signal, the second flag that is coded is arrangedafter the third flag that is coded, in the decoding, the second flagthat is coded is decoded after decoding the third flag that is coded,for each of the at least one of the nodes.
 8. The image decoding methodaccording to claim 3, wherein each of the quantization coefficientsincludes a luminance quantization coefficient, a chrominance Cbquantization coefficient, and a chrominance Cr quantization coefficient,the first flag includes a second flag, a third flag, and a fourth flag,the second flag indicating whether or not the luminance quantizationcoefficient exists, the third flag indicating whether or not thechrominance Cb quantization coefficient exists, and the fourth flagindicating whether or not the chrominance Cr quantization coefficientexists, and the third flag that is coded, the fourth flag that is coded,the second flag that is coded, the luminance quantization coefficientthat is coded, the chrominance Cb quantization coefficient that iscoded, and the chrominance Cr quantization coefficient that is coded arearranged in order in the coded signal, and in the decoding, for each ofthe at least one of the nodes, the third flag that is coded, the fourthflag that is coded, the second flag that is coded, the luminancequantization coefficient that is coded, the chrominance Cb quantizationcoefficient that is coded, and the chrominance Cr quantizationcoefficient that is coded are decoded in order.
 9. An image decodingapparatus, comprising: a decoding unit configured to decode a codedsignal to generate quantization coefficients and pieces of managementinformation, the quantization coefficients each corresponding to acorresponding one of transform units, and the pieces of the managementinformation indicating a structure of the transform units; an inversequantization/inverse transform unit configured to perform inversequantization and inverse transform on each of the quantizationcoefficients, eventually generating prediction error signals of therespective transform units; and an addition unit configured to add atleast one of the prediction error signals to a prediction signal foreach of coding units each including the transform units, eventuallygenerating decoded signals for each of the coding units, wherein thequantization coefficients and the pieces of the management informationhave a tree structure, each of the transform units corresponds to acorresponding one of leaf nodes in the tree structure, and the decodingunit is configured to decode, for each of the leaf nodes, a coded pieceof the management information and a coded quantization coefficient whichare arranged in succession in the coded signal for the each of the leafnodes.